I don't buy that at all. Politics are cut throat and this isn't even on the radar of the things he's done. I'm also not lowering the bar for Trump on this one - Clinton tried to play his game and failed. The best way to win at Trump's game is to not play. It's not likely to affect her, anyway.
You are lowering the bar for Trump with this one. This sort of thing has simply never been done in politics publicly. There is no honest equivalence between Cuban and Flowers, although you can attempt to keep trying to build one if you like. One is a political figure for the campaign, and the other is a nobody dredged up out of the past to make a personal attack that has nothing to do with the candidate's fitness.
Treating this as reasonable shows you've lost your way as much as any Trump supporter.