But I still don't understand how something as simple as the holy grenade is "too much". It's just a single random grenade chillin on a box or wherever in a corner somewhere with the name "holy grenade".. I hardly see how it's game breaking for anyone even if you found it without having wild wasteland.
Because it wouldn't just be a grenade named "holy grenade". If the easter egg is remotely similar to the same one in Fallout 2, it will have its own model (a gold grenade with a metal cross on top), and will have the destructive power to one hit kill anything in the game. Oh, and you had to get past a massive fight between King Arthur's knights in Power Armor and a rabbit to get it. Not exactly low-key, you dig?
Besides, the Holy Hand Grenade is a confirmed easter egg if you have the Wild Wasteland
trait. (Yeah, I guess Sawyer just had a slip, Gizmo, because he did mention in the same interview that you chose whether or not you wanted Wild Wasteland at the beginning of the game.) If you don't have the trait, you'll just find a mini-nuke instead.
I wouldn't be upset to see it in a normal game if the joke were as simple as you suggest, a regular grenade, perhaps found on a church podium, that says "holy grenade" when you look at it. That would be subtle enough for me.