If you've grown tired of your recruits getting slaughtered, I've unearthed a remedy.
Note: You don't have to use cheats; cheats just facilitate the process.
Get to level 2 of the Firefighter missions with there being a Grove member in the care alone. Next, spray him after spraying the vehicle. Here's where it gets tricky: After spraying him, if he is wielding a gun, exit the firetruck without pressing the mission cancellation button/key (even though this also ends the mission) then recruit him. If he was unarmed or was wielding a melee weapon (example: knife), you must press the mission cancellation button/key after spraying him before getting out and recruiting him. Seeing as Grove rarely ever are in burning vehicles, it's best to activate the "gangs & workers" cheat (the one where only Grove, Ballas, Vagos, and cabbies spawn) to speed up the process. He will be invincible; non-player induced explosions won't even damage him provided he isn't in the car while it explode; player induced anything will. Party time!
-King Andreas (Discoverer & PS2 tester)
-DarrinPA (XBOX tester)
-0909090 (PC tester)
-Khsh97 (Android tester)
-Militia (PS3 tester)