Creativity is a funny thing because most (or too many) people that come to the classes, or perhaps think about coming to the classes, are afraid of it because they don’t believe they’re creative.
I hear that a lot, particularly from blokes that say: “Oh, I’m just not creative.”
If the author had replaced the term "UX" with design, then the article would make more sense to me. To continue with the misuse of UX in IT to mean fancy and unnecessary design seems quite strange, because design has always been a factor in how successful projects will be (not just the interface but the whole process of delivery on an outcome).
Given a choice to pause and ponder versus jumping in and saying something that you might regret, I would always pick the latter.
Most of the time, people who are 'quick-witted' have either come across the situation before and recalled a good response (think chess players memorizing good opening or endgame moves), or that they are actually really good at analyzing and solving a particular type of problem really well (think prodigies that have an abundance of natural talent).
This is something that you can practice by listening to what other people say and analyzing the situation rather than jumping in with a comment of your own.
In time, you'll be the one jumping in with the 'quick-witted' comment.