When you tighten the nut onto the tank the sealing is taking place between the spigot on the tank and the body of the petcock, not on the the threads of the petcock nut.
The petcock body and nut swivel for positioning.
You can jb weld the nut onto the spigot it does not matter, what matters is as long as the petcock body draws tight with the o-ring sealing washer between it and the sealing surface of the tank spigot it will not leak. If there is no seal here, it does not matter what is on the threads. I gave you the part # for the Honda gasket in the other thread if it starts leaking again. Chances are you got the o-ring in there now squished just right and it sealed up and will be okay for awhile.