I had the problem with the thread too, so I made my own magnetic drain plug with a rare earth magnet glued onto the existing plug with JB-Weld. I keyed up both faces first with a dremmel, drilling holes for the glue. The rare earth magnet had such a strong pull on the drain plug, I doubt it will come adrift, and the JB-Weld from past experience I know is good in engine work. Incidently with the drain plug fitted one can stick a spanner to the hex head under the bike, so strong is the magnetism.

( JB-Welded a cylinder head onto a landrover engine when we blew the head gasket out in the sticks, and used the same glue many times with repairing plant engine casings.)

Yeah, there is always the possibility the glue will fail and the magnet getting itself into the oil pump, but that goes with anything bought, anything can fail and stuff up something else.