Some points in here probably are reasonable - e.g. “If you have a story to break, the BBC platforms are your priority, even if it takes slightly longer”.
However the policy doesn't seem fit for purpose and is a bit vague in areas where it shouldn't be.
Who's deciding whether a social media account is "an account which reflect only one point of view on matters of public policy" is a grey area (and hard to police - there's always new accounts popping up and who is responsible for judging this, how often would they be judging this). Similarly too what's deemed a “controversial topic" is a grey area and not clear and is the typical BBC issue of trying to create a 'give both sides' narrative in the name of "balance" when not both sides are equally reasonable and deserving of equal coverage.
The discussion point that seems to be doing the rounds this evening is sexuality. The optics of punishing employees in 2020 if they were to support people who are LGBT (e.g. maybe a close friend or colleague who's just come out or who may be LGBT but been abused in public as an example) is awful and would make it appear as if people being LGBT is "up for debate". Even if that's not the intention as Munro's tweet seems to suggest the wooly wording of the policy doesn't make it explicitly clear if something like sexuality is a "controversial topic".
Basically the Beeb had two options: use a 'common sense' type policy when it comes to have employees use social media (so leave it to employees to judge and reprimand them if they're deemed to have crossed the line) or to do an explicit policy explaining what is and isn't acceptable with a list of clear, explicit criteria so even if controversial (I don't think firms should be overly policing what employees do in their own time as long as it doesn't bring the firm into disrepute) everyone would know where they stand.
What the BBC have ended up doing is neither and something which feels 'designed by committee', has created as many questions as it's resolved and probably pleased nobody. The BBC really are their own worst enemy at times.