It’s all teenage attitude without pragmatics.
Simply put, if we’re 100% not going to go lower than EU standards, only higher - why would we not sign a guarantee on that to settle EU27 nerves and get deeper access to the huge market next door?
Look at the EU science programme. If we sign up to be a country whose institutions can receive & distribute money from the EU kitty, who oversees that legally? Clearly the ECJ - the Swiss do it that way.
If there is any legal/financial dispute between partners, the ECJ sorts it.
Where would a French uni saying it has been short-changed by the Swiss coordinator go? To French courts? But they have no jurisdiction over the Swiss institute. It’d be a mess.
Money from EU kitty needs EU oversight. That’s the ECJ.
Just like when you visit the US, you have to operate under US law & jurisdiction.
It’s fair & sensible.
Which is why saying we’ll have no ECJ is just a daft stance re: science prog.