Ah! I was not aware of these custom stems. Makes sense, as they would be stronger.
I avoid red locktite (even blue) on such small diameters personally because maybe the stem needs replacing, but not the crown (or vice-versa) and I like to have a "get out of jail" card... I don't like to heat the crown and the purple has held well for me so far... This is important to me on vintage Rolex where you might be working with an irreplaceable (at least difficult/expensive) 700 crown for example.
But I understand an OEM wanting to be sure that crown WILL NOT come off the stem, and generally you replace both together when you have a parts account.
I'm not a professional watchmaker, so I defer, but just relaying my personal experience.