Is leveling off crimson ore spawners within the rules?

I wouldn't want to abuse an exploit, but I've noticed that unlike every other spawner in the game, the flowers around crimson ore spawn mobs that give experience, so it's possible in principle to xp farm off them; one could even afk farm multiple levels if you can get the situation right so you don't die to rares or accidentally kill the flowers off.

It would take forever to truly level with them, I guess.

When I noticed that they kept on giving xp I tried a bit while leveling. To me, it was not worth it since I could make much more xp regularly.

I could try with my jugg by sitting in a corner but I think it would be just a waste of time.