It's literally what happened.

Cameron was trying to reduce the scope of EU integration with the UK (esp freedom of movement), with the threat he didn't want to use of a referendum, the EU said no (as the other commenter explained partly to disincentivize others, but also because they thought he was bluffing and people would never vote to leave), so the referendum was held.

To be fair, freedom of movement is one of the core principles[1] of the EU.

Restricting that is a tall ask, I wouldn't describe refusing that as being inflexible.

[1]: https://european-union.europa.eu/principles-countries-histor... "Freedom of movement gives citizens the right to move and reside freely within the Union."

I kind of made a point like this in the other thread - during Brexit it was a very hard No from the EU that they couldn’t negotiate on key points such as freedom of movement, and countries are either IN and have everything the EU comes with, or they’re out. Now, it seems, that Canada is being offered a favourable half-in arrangement simply because they’ve never before been involved. Seems pretty bizarre and arbitrary for the EU, but also totally standard for the EU because it’s bizarre and arbitrary.