Of course it’s invalid. Either there is something about the substance of the article that is debatable or there isn’t. Other opinions are completely irrelevant.
If I write an article about the benefits of X drug and have expressed publicly by other channels my support for the company that produces such drug, I think is relevant for the discussion of the article I just wrote. That's why I said that may be it is not the case here, as I my self don't see any relationship between the linked tweets and the article. But I don't think is to crazy to think that two related opinions can be analyzed together regardless of the channels of distribution.
If you write an article about the benefits of X drug, you have presumably made arguments that can or can not be supported with available evidence. Your other interactions with the company producing the drug are irrelevant.