As a motorist, I'm letting the cyclist go first regardless. I understand what effort it takes to stop and restart a bicycle as a human powered engine vs what the machine I'm driving can do with the lazy effort of brake and accelerator pedal.

As a cyclist, I'm going to point and wave a motorist if I decide to let them go first on their left turn. There would be no confusion between that and offering a traditional turn signal. To be honest, it's probably why I don't signal a turn in the first place. Several reasons apply.

First a motorist really should perceive a cyclist as a pedestrian in terms of the damage it can do to bike and body in a collision.
Second, it's the precious time and hand that I free to release that is unable to be used to apply the brake lever to stop in an emergency situation should the confusion result in that. I'd much rather have two hands on the handle bars to hold the front wheel in place at an impact. Granted one handed or two handed is going to suck in a collision, but a slower collision, I might be able to maintain staying upright than being dumped to the ground in a situation where the collision is one where the two of us is almost completely stopped.
Third, if the motorist has to assume I'm going straight and provided they see me, they are simply more apt to allow me to proceed first since they are turning left. And if the motorist is coming up from behind and going to try to beat me to the turn and potentially right hook me, they're going to try that regardless. Otherwise they will stay back, assume I'm going straight and make their right turn behind me, which is effectively what they should do anyway, right ?

My goal is to be in the most control of any situation that arises, whether it works out that way or not is debatable, but from my perspective, at least I tried everything at my avail. And if I'm going to be injured or die, so be it, at least I know I did that for myself. I know others may perceive it differently, but in the original situation, the worst you can do by not signaling is piss a motorist off for not signaling. To me I'd rather that be the case than both of us getting agitated and irritated at the other for the stand off for both stopping. See in that, the cyclist confronted the motorist, had asked them and put them on the defensive to rationalize that split second. Without having signaled a right turn and the motorist would've had to have made any inquiry or remarks. Perhaps both parties being at the same party the motorist and cyclist just move on without any verbal confrontations. Meet the host, enjoy the food, beverage and entertainment ? It's no big deal for either. Enjoy each other's company and not potentially ruin the party over an argument of who was right or wrong ?