In other versions he threatened her and she picked up a brick but didn't throw it. My guess is throwing it would have been pretty dumb, but YMMV.

When she was ten, a white boy threatened to hit her. Rosa picked up a brick and dared him to. But when her grandmother heard about this, she scolded Rosa severely

But still, I hadn't realized Rosa Parks was 42 at the time of her arrest (and yes, she'd been with the NAACP for 13 years and active much longer; it just happened that the particular bus incident was unplanned, but the bus boycott movement among other efforts was well established).

Perceptive comment, aa.  (please pardon--remainder of this comment is an attempt to respond to comments or questions made by others as well as you in this thread) I think she was "ordinary" in the sense that most people seem to think of it, as a person without formal titles or high official positions.  She was an active citizen, she was highly respected apparently among her peers, and she was courageous.  As are many extraordinary "ordinary" citizens.  She projected as relatively relatable. 

And she was a she, making her almost automatically less threatening from a public relations standpoint.  Had it been a black man who did just as she did, however "meekly" he was viewed generally and during the incident, would the Montgomery bus boycott effort have taken a very different path?

Decisions Gandhi made about how he was going to live his life were deliberately made to maximize his ability to present as not an elite, but as someone who, if not "ordinary", demonstrably understood what life was like for most of the people he was recruiting because he was living, relatively speaking, more as they were.  And so he was much closer to being relatable on that account. 

He understood how the symbolically laden strategic and tactical choices were critical in his case.  In his case if he was able to recruit large numbers of ordinary Indians to engage in non-violent, disciplined actions, that was the way he was most likely to raise the cost of continued colonization by the British enough for them to conclude they were better off leaving. 

King, by contrast, knew that because blacks were in the minority, the effort he was figuratively leading needed white support to prevail.  Thus his symbolic decisions, re dress, choice of tactics, style and substance of speech, etc., were aimed at walking the treacherous line between confronting the local white power structure while at the same time winning over his "swing" local and national audiences.  That started with not giving his target audiences easy ways to dismiss him (by dressing like, say, a hippie, using slang, seeming not to rule out resort to violent tactics, all automatic turnoffs if not non-starters for many white people, at least some of whom he hoped or needed to win over.)  Unlike the case with Gandhi, his formal dress, style of rhetoric, etc. were not going to alienate many blacks because he was a preacher and he was dressing and speaking in ways that were culturally well-established and not only thoroughly acceptable, but widely admired and respected in black communities where he was active.    

Trump wants to provoke and trigger an excessive reaction among his opponents.  Depending on what reactions he can provoke, he may choose to respond with repressive measures.  This dynamic occurs frequently in other countries, from whose history we might learn if we are not learning it from our own history.  Any head of state can do so.  In the US, it can matter a lot whether, in adopting repressive measures, the head of state has public opinion on their side.  So it behooves the Trump opposition to do everything it can not to end up on the losing side of public opinion with respect to specific actions that are taken and incidents that occur.

There are Trump supporters who are suggesting that overt contempt for Trump could well re-elect Trump.  https://www.washingtonpost.com/opinions/the-lefts-contempt-is-going-to-r...  I think they are not at all clearly wrong on that point.  If the opposition leaks too much discipline and smarts, increasingly less unfavorable, or even favorable, public opinion is one thing Trump and the GOP members of Congress could end up having in their favor going forward.  This could work to the GOP's advantage in the upcoming elections.  Less unfavorable, favorable, or trending in his direction public opinion could reduce any inhibitions (are there any, at all? Perhaps not.) Trump may have in terms of what he will do.  And even if it has no impact on Trump's actions, public opinion and trends can impact members of Congress and other Administration officials.

By the above, I reiterate that I do not mean therefore, that I hope the opposition will "do nothing."  Protest activity that is coordinated, has clear objectives, uses thoughtful means, etc. can be beneficial.  But, for example, devoting time to voter registration in strategic areas is likely to help, and, in contrast to some of the actions being urged now by some, has no real potential downsides in terms of the fight for public opinion going into the elections.  So for those who want to "do something", it's a much less risky and more predictably productive thing to do than to go out and harass Scott Pruitt.