I would consider this every bit as bad. “We marked our own homework! And guess what? It was great!”
The whole concept is ludicrous.
Internal audits still have value as it means that someone can't steakily steal money from the reserves without them noticing.
Further, they paid $41 million to settle a case over their lies - https://fortune.com/2021/10/15/tether-crypto-stablecoin-fine...
I don't think it's a stretch at this point to say they have a history of, at the very least, being highly economical with the truth and misrepresenting their own level of transparency. And I do think your argument is unreasonable.
Take a look back to 2017 on the wayback machine -
"Every tether is always backed 1-to-1, by traditional currency held in our reserves. So 1 USD₮ is always equivalent to 1 USD."
"Our reserve holdings are published daily and subject to frequent professional audits."
We know that neither of those things was true.
Have you considered they may have audited it themselves? Just because there wasn't an audit published by an external auditer that doesn't mean no one has ever audited their accounts.