Unfortunately they won’t spin round. With the 2020 frames they’re basically all going to crack, it’s just a matter of when. If you’re getting a good deal then go for it.
I’ve also been quoted only a couple of hundred from the guys at carbon repair in Surrey to sort it all out and add strength once it goes
There's a little nubbin that is supposed to stop the bars over rotating and smashing the top tube in a crash but all it achieves is a dead frame and / or fork. Some folks have achieved this without even crashing, i..e letting the bars flop around when the bike is lifted by the top tube.
Unfortunately they won’t spin round. With the 2020 frames they’re basically all going to crack, it’s just a matter of when. If you’re getting a good deal then go for it.
I’ve also been quoted only a couple of hundred from the guys at carbon repair in Surrey to sort it all out and add strength once it goes