Both of those threads agree that no sealant is necessary ...at the CGA connection between the nipple and cylinder threads. The first link is specifically about that connection. The second link is a number of people weighing in on different types of connections, but consensus seems to be that on tapered fittings like NPT (which is virtually everything we (hobbyists) use in the US, aside from the cylinder fitting, which utilizes a washer instead of sealant), some sort of sealant is necessary. Such as teflon tape.
Again, loctite, teflon, and pipe dope are all sealants that will work for our purposes. They all have pros and cons. Not going to argue this further.