Shareholders would increase the authorized outstanding shares as soon as it was asked of them. It's a mere formality.
If you are saying Tesla can't do a 5:1 between now and that formality, then I would suggest you are not looking at the bigger picture.
The issue was if Elon could surprise us with a split whenever he wished as you phrased it.
Since a vote, even one that's certain to pass, needs to happen to authorize more shares first- he can't (unless it was a very small split as noted which seems very unlikely).
I'm looking at the next 5-10 years in general. And I do believe Tesla could swing a 2:1 at any time.
Pretty sure several folks have pointed out why they can't- given the # of authorized shares, and the # needed for SBC.
It's more like 1.9:1 at best with current share cap.
Again all of this can easily be "fixed" by a vote to authorize more shares, but a 2:1 or greater split can't be a "surprise" ahead of that happening because there's not enough shares.
Additionally, I tend to believe what you term a "small split" would not be small in terms of repercussions. Namely, any dividend stock split would have essentially the same effect, without a massive capitalization by those who had created large numbers of synthetic shares, it would require all naked short positions to be covered.
I know there was tremendous debate between a lot of folks on if that's really the case or not.
But let's consider it from this perspective regarding "small" splits.
Do you agree Tesla (and Elon explicitly) dislikes shorts and would like to burn them and dissuade them as much as possible?
If so (and I think the evidence is pretty clear it's the case)... AND every stock dividend, even a tiny one, screws over all the shorts.... why wouldn't they just issue an exceedingly tiny split on a relatively frequent but irregular basis- to routinely screw over all the folks naked shorting the stock?
If it's as simple to screw the shorts as ANY stock dividend, and Tesla hates shorts, why only the 1 so far?
Why would they NOT be sticking it to shorts multiple times a year until the shorts stop bothering if it's that simple?