I thought the disputed claim was that companies don't make nuclear PPAs because of lack of interest. In that case those claims would combine into a very flawed argument, but pinewurst isn't saying that.
But if the actual meaning was that companies don't invest in the power plants needed to fulfill the nuclear PPAs because of lack of interest, then yes pinewurst was saying that, but that's not a circular argument anymore. "Nuclear PPAs don't represent real interest in power plants." and "There's negligible demand for nuclear PPAs for actual power because there isn't real interest in power plants." are compatible statements and not circular at all. The implication is simple: PPAs are a useless signal, and if you want to check for meaningful interest you need to check other signals. I don't know if I agree, but I think it's a reasonable position. And there's no 'conspiracy' needed.
Are the people you're talking to in support of the first quote?
I would expect them to say a lack of PPAs shows lack of confidence, or for them to barely care about the number of PPAs. Not to use it as evidence that there's no interest.