Well, you're clearly an advocate for labor so I'm not going to here try to convince / sway you to some different viewpoint.
I'm just going to correct your "facts" for other people reading the discussion.
"as it’s [$15/hr] proven it’s sustainable at scale"
That's a total guess / assertion in favor of your position, isn't it?
The new wage being offered isn't proven "sustainable" -- it's merely what some employers have had to offer in the face of a pandemic + widespread increased unemployment benefits. And we're seeing record inflation (with some part attributable to this, some due to other important factors of course). So you're hardly justified in saying it's proven sustainable long term. You just want it to be so because it benefits you.
And secondly, and more importantly, your tactics are no better than some corporatists who seek to exploit laws to their advantage whenever they can, just for their side, because they can. "... which makes it easier to lock it in with statue."
If it were so proven to be good and sustainable, why is a statute required? Wouldn't that sustain itself?
Now that you see a moment where $15 has been tried out of necessity due to the temporary (hopefully) situation, you want to "lock it in" with laws and regulation, and distort how the market for labor works by putting in a floor.
I find it equally bad for someone to try to argue for and do this, regardless of whose side it is -- corporations trying to skirt environmental regulations, other public obligations, or labor trying to say that they deserve x/y/z because they got it for a moment.
Don't act as if you're trying to find a solution good for the entire economy, producers, consumers, workers, people. You're an advocate for labor to get more benefits. And using incomplete arguments that favor your position.
And by the way, I don't engage in the practice of downvoting people who I merely disagree with.