Being criticized for not having "comebacks" - my, how telling.
The "comeback" is something distinctive about psychopaths, not intelligent, conscientious people. This feature is described in all of the literature but just for example try "Without Conscience" by Robert Hare, his section on Glib and Superficial, paraphrasing:
Psychopaths can be witty, articulate, and quick with the clever comeback. They can tell stories that are unlikely, given what is known about them, but exhibit a smooth lack of concern about being found out.
In all these pages, not just here but since the first pages on bigfoot on the Randi forum - there is no evidence of bigfoot but instead it is mostly a long series of "comebacks" by proponents, (gotchyas) the backstory to it all being extremely unlikely, with a rather remarkable lack of concern for how they look. This is not distinctive to this one person - it is pervasive across all of the personalities we have engaged with. As you delve deeper into this literature, and in particular descriptions of psychopaths like this book - like being grandiose, lack of remorse/guilt, lack of empathy, deceitful and manipulative ... it becomes rather striking that you are looking at a training manual for psychopathy when it comes to bigfoot advocacy against people who would question it.
I am not proposing bigfoot proponents are all psychopaths, but rather that their approach to interaction with others is the kind of behavior a psychopath is known for and is not something to be emulated.
You can't shame a skeptic or a scientist for lack of "comebacks" because there are two things about their training that make them the wrong personalities to expect them from. First, "comebacks" are put-downs of others and a person with a conscience is not stupid - they just feel bad about being mean to other people. But secondly, science and skepticism are approaches to subjects that take long trains of coherent thought rather than the disjointed series of one-liners we see out of woo practicioners.
Was James Randi known for quick comebacks? No, he was known for exposing charlatans - demonstrating how they did it. It is right and proper that we study how woo practicioners operate, and the "comeback" is their gimmick, not ours.