I don't know how many marketers you know, but the ones I know would be perfectly comfortable bringing this up. It's kinda their job to know about this sort of thing.

Matt Cutts' wife used to pass out "porn cookies" if anyone found porn with safe settings on. Google's culture is very permitting, so I don't think it's much of a problem.

Statistically close to half the people in that meeting watch porn on a regular basis... so maybe one of them.

Wouldn't a Google search of this branding have done the trick?

It won't be a problem - Alphabet will just "make them an offer they can't refuse" and within a year, RedTube will re-direct to Youtube Red. (The offer being, let us buy your domain name for a reasonable price, or we'll sue you out of existence.)

lol on what grounds could Google possibly sue RedTube? They don't own the word "tube", which has been a reference to television since the beginning. I don't think you know what you're talking about.