I'm in the possession of this axolotl now due to some problems with his family not complying with it's care, and he's with my other 3 that are about the same size, and the 3 snails with all 4 of them, the snails are fine. They clean the algae of the deco and glass and they eat any uneaten food, never have I see my snails go for the axolotls, and if they do, the axies usually bite at their tentacles or eyes for lack of a better word. The snails don't pose a threat the way I see it until the axolotl reaches a big size, big enough to get the snail in his mouth, and even then, the risk is VERRRY LOW, but at that point, I'd either remove the snails entirely or remove them and get some big snails that they couldn't fit in their mouth. The snails are very docile and don't care too much about the axies, besides pooping all the time, they're good to have with them, especially the babies this size, pooping all the time, the snails help clean up a bit, even though they don't "eat" the poop, they eat some stuff inside of it.
I have 3 snails with my 2 six inchers, and they're fine, the axolotl's head can't get stuck like that nor can the axolotl eat the snail. And the baby that the OP had, he's around 4 inches or more now, as stated earlier, he's in a 30 gallon with 3 snails and he can't eat the snails obviously nor can he get his head stuck in the snail, or it'd be near impossible for him to, he'd have to SHOVE his head in there, with force. I've never seen my snails suck onto my axolotl AT ALL, and if the snail gets close to the axolotl, like behind him and freaks him out, the lotl just moves away from it, but even this rarely happens, the snails don't really show interest in the axolotls whatsoever.
I'm sorry if I come off as irresponsible, or ignorant, but that's just what I believe, when they get bigger, and can swallow the snails, I'll remove them and not stick to snails anymore, or as I said earlier, get bigger snails that they couldn't possibly fit in their mouth. I just don't see any of the risks that you stated as viable for axolotls at basically any size unless they're close to what his axolotl was when he posted this originally, unlike the size he is now, 4 inches and above should be fine, unless we're talking about adult size that can swallow the snail, I'd intervene if that was the case.