I'm American

Here we go.

so I don’t understand why the UK has a ‘Ministry of Truth’

Ofcom aren't a ministry of truth, they're not affiliated with the government in any way. They are an independent regulatory body. Surely as an American you're familiar with your own FCC, yes? They serve the same function.

As for the content of the article itself, I agree that Ofcom should investigate. I don't see the problem having clear lines between politicians and news anchors. I actually don't think a politician should have any additional job or career that could cause a conflict of interest.

Edit: After perusing your comment history you're clearly a homophobic, transphobic climate change denier who just loves posting in communities you disagree with to engage in bad faith arguments. Thus I want nothing more to do with you and have blocked you.

We've some similar nefarious influences that would love our media to descend to the full depths of some of the American 'entertainment' news media. But were not quite there yet and its still a fringe atm.

So sitting politicians doing backdoor propaganda still isn't allowed by the watchdog.

The government of the UK is saying that MPs who serve in parliament shouldn’t be featuring on news programs. It’s their own law that they themselves set.