I once spoke at a conference where a well-known member of the software community saw fit to interrupt my presentation with a correction (related to some political issues of marginal importance to most people).
It was rude, in poor taste, and created a tense moment for everyone in the room.
It would have been easy to posture and fuss, asking her to interrupt someone else’s talk instead of mine. And I would have been completely justified in putting her in her place (I had the mic, after all) while it was happening.
I patiently waited for the interruption to end (it was brief, thankfully), allowed a silence to hang in the air, and continued with the presentation.
Afterwards, she apologized.
I try to remain cool under pressure at all times, and there seems to be a wellspring of patience to draw from when challenging situations arise.
This isn’t to say that the enthusiastic assertion of one’s will is never appropriate — the key is knowing when each is appropriate.