A few months ago I raised this issue directly with one of the mods and was advised that the deletions of my threads were "by peeps much higher up the food chain than us mere mods".
I now work on the basis of expecting a thread to be deleted. If it isn't, that's a bonus.
I've learnt that Lonnie Donegan is a "No,no", however, toddlers swearing seems to be OK. But I haven't figured out where the deletion threshold lies