If you're not trying to impress people, why are you spending so much effort communicating your opinions on this topic? I see that you mean to posit the large black hole just to account for the colliding galaxy observation and perhaps not as a general mechanism to account for missing matter wrt galaxy rotation. My apologies, since I seem to upset you, but I stand by my opinion that the arguments (yours and others) for and against in this forum should be taken with a huge grain of salt: it seems to lack input from experts in the field. So I don't take it seriously.
PS - I like your T-shirts.