I had the front valve stem separate on the front tire of my Valkyrie instantly making the tire go flat at 80 mph on the super slab. The bike did not go unstable just took more muscle to steer.
I'm glad that worked out for you!
After all, you are probably riding when you get the flat in the first place so why is the risk of plug failure any worse then risk of any other kind of flat?
The difference would seem to be that most punctures are partially self sealing by the offending nail-spike-bolt-etc, and even if the hole doesn't still
have the offender in it, the tire usually slightly recovers and the air
seeps out.
*If a plug comes out after miles and months of cord rubbing, tire flexing,
and holding the hole open, it will most likely be a fast deflation. If it happens on a super slab maybe just an inconvenience (hopefully),
but leaned over in a turn, maybe quite a bit worse. I'll admit that I've only had one flat in an un-tubed motorcycle tire, (
The first day I brought my brand new connie home. )
My lack of tire failure experience may be the cause of my cautious approach but then maybe I'm just a chicken $#!+.
*Further experience has changed my opinion...I now believe differently.