And just so there isn't confusion, let me make sure this is clear. (I've seen the debate so many times because the detail is in the S)
You must use plural 'stopsounds' in console.
No S does require sv_cheats.
That being said ... his suggestion might have some merit, but not for the reason he states.
I used ulx playsound to play a sound to a server the other night.
The sound, played in Source games, loops. I didn't know this (It's title didn't have 'loop' as so many of the sound titles do)
It continued looping until I and the clients used stopsounds in console.
Perhaps a ulx stopsounds wouldn't be a bad idea after all.