When first using FLARM about 10 years ago, I don't remember anybody whinging about being unable to use FLARM for tactical advantage in contests. Those contests were FLARM mandatory.
Not competing, but worked at two 60-glider contests around then. The only complaints were due to people running an old software version, ie 2.x instead of 3.x. This was easily fixed.

Somehow I don't see that mandating FLARM and in stealth mode at contests is a barrier to contest entry. Rentals are inexpensive! From williamssoaring.com:

PowerFLARM Rental Units Now Available in the USA $50 per Contest ($100 if you have previously participated in the rental program)
Glider and tow-plane pilots can rent a PowerFLARM unit for $50 per contest or similar event. The $50 includes postage and return postage.

By not using "the dark side" of the instrument, there is nothing for a first-time renter to learn about tactical use, so the pilot is not at a tactical disadvantage or heads down trying to figure it out.
Jim