That is not it, it is more like I am not going to do this because I said I wasn't going to do it in session 0, we will change it in the next game.
I do this, in session 0.
I find that discussions like this in the middle of the campaign sometimes cause problems. You presume everyone in the party will be ok with it, and in that case sure there is no problem. Often though one guy isn't ok with it and either he stays quiet about it so as not to go against others and then he feels cheated or he is honest says he doesn't want to change and then the guy who wanted the change feels slighted by others in the party.
I think it is easier and better just to let him get a different feat if he wants and we can change the rules when we play the next campaign campainn, which is only a few months away.
Quite the opposite. We all agree in session 0 to the rules and what homebrew we are going to use and we also only deviate if it causes very serious game play problems.
Sure if they buy in. Not so simple if they don't and we ALL already bought in to which feats we were using and which one we weren't.