Earlier quoted context omitted.
I more or less agree with the "no politics at work" stance but you've omitted his recent "contributions", where he went completely off the rails have a read of this https://world.hey.com/dhh/as-i-remember-london-e7d38e64 it's completely unacceptable, and he's promoting a self proclaimed fascist white nationalist (Tommy Robinson)
(political opinion incoming) Other than his mention of Tommy Robinson, it is not radical or unacceptable to say "Wow, my city has changed radically in the past 20 years and is losing its identity". If the center and the left completely reject the validity of national identity and the expectation of immigrant integration to British identity, then you leave people with those sentiments running into the only open arms l…
He explicitly cited race, not "British identity" he quoted a Wikipedia page where he took stats excluding non-white British.
I don't think he was arguing the point you're attributing to him.