Open U.P. Thruthread hanger with trainer?

I have an Open U.P. with the Thruthread derailleur hanger, which is used to lock the thru-axle and the hanger at once (video description here).

I use an old Kurt Kinetic wheel-on dumb trainer, with a Blackburn thru-axle that is designed for trainers.

My question: The Thruthread requires a tiny threaded cap on the drive side, which locks the hanger in place. But when I use the Blackburn thru-axle, I can’t use the cap, which in my understanding means the hanger is not locked to the frame (even though it is all sandwiched in due to the trainer’s clamps).

Is this a problem?