"speculated wrongly that I engage in secret product placement"
She doesn't get it, does she? Every bit of her 'journalism' is about product placement. Take the products away, and there is....nothing. She doesn't write anything without product placement. She's not a freelance journalist who does a bit of product placement, she's a freelance advertiser who (sort of) does a bit of journalism. She doesn't like to admit that and it's where she's blind to herself.
As an advertiser, she has to comply with the law. She doesn't think she does, because she thinks what she writes is journalism, but without the product mentions, her writing doesn't make sense. That alone speaks to the balance of what she's doing.
Her Guardian column is just one long advertisement (one which the Guardian are probably happy to go along with as they pocket the cash from the affiliate links and pick up beauty advertising in the paper/magazine). It's only beauty, and the income covers her fee and makes them a bit of money. The beauty department wipes its face financially, so they keep it going despite it being long superseded by the selling power of social media.
It's interesting that there is no column this week. I'd love to know whether it was written and submitted but pulled, or whether the break was already arranged.