Why? I'd literally take Chris feckin' Wilder over ten Hag at this point.
Tuchel, Amorim, Motta and De Zerbri would all be fine. Especially the first three.
Inzaghi is already a very good manager. He's been managing for 8 years now. He did a very good job at Lazio, and has taken it to another level at Inter.
While Italian players rarely do well outside of Italy, Italian managers have generally done very well in The PL. I'd take him in a heartbeat.
My mindset is like this:
Ten Hag is very likely not to be the United manager in 3 weeks time. But if he stays, my assumption is that it's because the "ideal candidate" is not (yet) available.
And it will be a stay of execution. If it's not vastly improved by October/November, he'll be gone. Early season, a top manager usually becomes unexpectedly available. So they might have a better chance of getting the right man then. Or Ten Hag does turn it all around somehow.
The above is not ideal. But neither is getting another manager now who doesn't suit how we want to play and isn't suitable to being the Manchester United manager. It's likely then in 2 years time we're in the same position as now.
In short, I'd rather United wait until the ideal manager is available, even if it takes a few more months. Rather than get the wrong person in now and have to persist with them for a couple of years. Then be tied to him when a the ideal man becomes available.
Another solution is getting rid of Erik and then getting someone like Solskjaer on a years deal with the agreement that he'll be replaced when the right man comes along. But I'm not sure who'd agree to that. And it probably wouldn't do the squad much good.