This is just a straight no. Heck, this is a big huge red warning flag that causes me to say something like, "I'm not sure this is the right table for you." This is a player manifesting massive dysfunctionality and I think most GMs that don't hurt for players would be happy in the long run they got rid of them. The motivates are suspect and the wheedling probably will never end with this player. Every single future stressful situation is going to feature this sort of bargaining as an attempt to solve the puzzle. There is no end of table arguments and rules lawyering I would expect from a player pulling this sort of crap.
The whole approach here of looking up a power build here and planning out 20 levels is sus, but the fact that he's not only looked up a power build but is like, "That's not enough power. I want more!" tells me he'll never enjoy a game he isn't the absolute center of attention of, and he'll do his best to ruin everyone else's game when he isn't.
This is not a point buy game. But if it was, basically shield proficiency would be 0 points because for most builds losing it means nothing. Anything you could exchange it for would be an upgrade because he's not planning on using it ever. Shield proficiency is a flavor option, that allows combatant classes choose a fighting style where the fighting styles are generally considered equal and balance. You lose basically nothing for switching between fighting styles in D&D. There is no preference here. Having a shield doesn't clearly make you stronger than using a two-handed weapon. There is no equivalence between the two things.
Try to tactfully explain why that's a non-starter of a proposition, and if it turns into a bargaining session do yourself a favor and kick him to the curb because it's not worth wasting hundreds of hours of your life trying to play with a dysfunctional player. And if he's a friend, well, the friendship is probably not going to survive playing with him anyway.