Taunt overide

Because he's stealthed, when he comes out of stealth he should be taunting again unless it runs out

WAI (unfortunately)
Taunt should supercede stealth.
It doesn't, if stealth is applied the taunt is dispelled.
The way it should work (imo) is that it the stealth should give the taunter a benefit (e.g. ×% dodge or ×% protection or crit immunity) for the duration of the stealth but not dispel it.

You can't attack someone who is stealthed. That's the point of being stealthed. Don't rely on RG's auto-taunt if your Teebo lead has a chance of granting him stealth.