WRNU244

I call BULLSHIT - just another Sad-HAM disguised as a GMRS user.  YOUR radio YOUR choice - if the sad-HAM control freaks dont like it, they can change the channel..  
HOWEVER - as you mentioned, if the repeater owner requests that you not use a roger-beep on his repeater, then following the wishes of the equipment owner who's equipment you are using would be the polite thing to do, IMO..

If what that person said is "the FCC does not allow new GMRS repeaters", then that person lied to you or is an idiot - likely both.