depending on who you "talk" to on the 'net depends on what kind of answer you get. Pedals definitely seems to be something you got to have to be a bike, though there are learning/training bikes for kids without pedals.
Me, I think that you should have fun with your build- if that means taking them pedals off, fixing them in place or stuffing them someplace dark well, then- its your bike and your build.
I've got 3 builds going right now:
1 madwagon friction drive
1 black OCC chopper Schwinn getting a chinese 2 stroke it will have pedals
1 blue occ chopper getting a 49cc 4 stroke off a pocket bike with a 4 speed CVT no pedals. I'm registering it as a scooter- same regs in Mass as a motorized bike. I pay my $40 and I can ride it to my hearts content for 2 years.
Each is a bike to me, but then I have to finish the other two
I'm too busy riding to get the others done! These things no matter what htey are- are the most fun you'll ever have on your bike.