Something useful to tell your friend, OP:
"Whelp, good luck."
You're not gonna convince him, likely, if he's spending money and then doing whatever they say. The only remedy is time and not being an asshole about it until he comes around. Or doesn't.
Either way it's not on you, and it's a recipe for frustration if you try to make it so.
So, force injures the body both when it's close to peak and when it's really far from peak, but in between it's innocuous?
And the use of the musculature in typing is different from other repetitive muscle contractions because...what, it's not done in the gym? Or is it the lack of sweat, perhaps?
Ok, I think it's time to just go here:
Squatting (or benching) in a Smith Machine is fake and gey. Carry on.