Far as I know, unless ODT has a policy, there’s no buyers remorse period for guns. It doesn’t sound like you told him if he’d waited a day the one he bought would have been cheaper.
I thought I was buying a rifle when I got my PC9 (PCC9?......it breaks down whatever it is) and while it wasn’t inexpensive it takes up about the same gunsafe space as my $149 Savage 22 that I don’t ever shoot either!