Their first example of "researchers believe" for example. If 'experts believe' something then surely (weasel words?) that should be given weight, even if they aren't offering a cast iron guarantee of fact. That's communicating nuance, not using weasel words. That isn't to say they can't be weasel words though.

There are a few (weasel word?) other examples that I myself have probably used. Maybe that's just British understatement?