It might have gotten threaded in wrong last time, or turned to tight.
There should be a rubber seal on it. Thats what mine has on it.
The seal might be missing and it is leaking cuz of it, thats why maybe they turned it to tight. to try and stop it leaking.
Or you might have another issue with a case seals. but Im not thinking that with the info you mentioned.
The difficult part, is cranking that nut off. it might break or strip the threads in the process.
I like PBR blaster, penetrate, works well, you might try it. but thinking you have more of a cross thread over tightening issue.
Now. If you are concerned about touching it. You can get a small hose and come in from the top and suck it out. with one of those sifon type small pumps. Its not gonna get all the sludge and crude at the bottom. but would allow you to change the oil. Without having to loosen the clutch case.
Did you edit your post ? as It looks like you removed some of the thing you were asking or mentioning.
Sporty