Talking a few days ago about reopening society after the lockdown, Boris Johnson said he was cautiously optimistic. Coming back to that topic last week, he said that he was now ‘even more cautiously optimistic’. He probably meant to say that he was now even more optimistic, but his careless phrasing was ambiguous. His words could easily be taken to mean that he was even more cautious in his optimism.
He could have have avoided the ambiguity. For example, he could have said: I am even more optimistic, though still cautious.
Maybe he was just careless in failing to eliminate the ambiguity. But it seems more likely that he was vacillating over what message to pick.