Loktite would just make it harder to replace a broken valve stem. I buy all my tubes with removable stems, so I don't ruin a good tire because I screwed up the valve stem. I carry a couple of valve stems salvaged from old tubes in my repair kit that I use on long tours.

P.S. We have been using tubes with removable valve stems for at least 12 years without having a valve stem come lose. We have a fleet of bikes in our family and all of them use Presta valve tubes. We put on a fair amount of mileage. My wife's newest touring bike is 8 years old and has 22,000 miles on it. She has 2 other bikes that she also rides.

About 75% of the Presta tubes we used during this time are represented by the number of valve stem bolts I'e been throwing in my tool box for several years. I just wanted to see how many tubes we use, and they are handy.