IME the BBC always goes easy on whoever is in power (or, near the time of an election, the presumptive winner)... this is quite natural since ultimately the government is in control of the organization.
It was said tongue in cheek as a response to unfavourable coverage. Job security obviously isn't a joke to BBC employees so there is always going to be a "don't bite the hand that feeds" rationale to reporting.
That said, I think some of Laura Kuennsberg's reporting has been so blatantly biased I'm surprised she's got away with it. In fact, she has had at least one ruling against her regarding impartiality, with a slap on the wrist outcome:
https://www.theguardian.com/media/2017/jan/18/bbc-trust-says...
They say there's no evidence of bias or intent but it means as much as KFC saying "we uphold the highest standards of hygiene and all our staff are heavily trained as such" in response to an employee pissing in the milkshake.
But in this case it's not the BBC refusing to play it... is it? I'm not too familiar with British radio stations, so those might well be BBC's subsidiaries.
Anyway, "this is quite natural" - I don't think the criticism was that it's unnatural, just ethically suspect.