Squawking 7700 does have some benefits. I was sitting at Burbank Approach when Alaska went in off shore. They were squawking 7700, which kept me aware that they could do anything, and it might not be wise to put an airplane in their way.
The aircraft was neither in my airspace, nor was I communicating with the aircraft via radio. But the message was received.
But, I would absolutely argue that informing ATC via ANY means would suffice. Naturally, if I have a radio failure, I'll squawk 7600 since I've lost my direct communication method. If there's a illegal intervention, I'll take care of that in the prescribed manner should verbal means not be possible, smart, or could be misinterpreted in some way.
Navy guys coming offshore with the P3's would regularly squawk 7700 when they couldn't get #4 engine started, after 8 hours of patrolling on 2.
I'd suggest not to do that, but I'm sure that they're just following orders.
Finally, the enforcement folks are COMPLETELY clueless as to what is going on in ATC land.