Have you heard the podcast? He says that he spoke to some engineers working on the NX and they told him that it's not going to be weak by any means, but not a powerhouse either. He added that they were very vague because they weren't supposed to say anything, but "not being on par with ps4" sounds very specific, so when he said that it was his take on what he had been told, not something that the engineers told him.
I've listened to that section of it several times yes
He says specifically, "What they were saying is that, you know, it's not going to be weak by any means, but they're definitely not trying to be a powerhouse competing with PS4. That was kind of the general sentiments of what they were saying in regards to how powerful it was."
The comment about them being "vague" was in regards to the unique aspect of NX that "no one has ever done before."
Maybe the part about PS4 was extrapolation on his part, but I don't think you can be certain of that based on his comments in the podcast. I remember his twitter posts too:
https://twitter.com/doctor_cupcakes/status/617098268674273281
Definitely implies this info is something he heard rather than opinion.
Of course, Tamaki doesn't have a perfect record by any means and his rumors have even been banned on gaf (making threads for them, anyways). I'm just relaying the history behind his rumor.