The problem with "they should have done" comments is that Radiohead want 100% and apparently won't accept less. And she won't offer more than 40%. So that's a massive gap.
If Radiohead refuse to accept less than 100% then their lawyer's opinions are completely irrelevant. They do as they are told by their client and nothing more. They may well have advised Radiohead to accept the 40%, or make a counter offer somewhere in between. But if their boss / client being Radiohead decide to ignore that advice...
Why would you think the lawyers would do this without specific instructions from their client?
And that's before we get to the issue that the decisions being made might actually be being made by the record label. Most record contracts allow the label to decide on all legal issues on behalf of the band even if the band disagree. Either way - that's still the client decision.
Radioheads LAWYERS do not accept or reject any offer. They only communicate the decision made by the client.