Don't worry about it. The slight amount of preload from adjusting the bearing correctly will hold the grease disc, and the inner bearing race reasonably still. It definitely won't rotate anywhere near wheel speed if it moves at all. If you're going to get all OCD about it, get the spindle and the disc super clean with spray brake cleaner, and stick the disc on with a few drops of super glue. It's totally unnecessary to do that, however, at least for the 50+ years I've been tinkering with these old rigs!
Jerry
