Definitely not, because technically, NameCoin didn't follow Satoshi's description:
You're right, it is not technically an exact implementation of what satoshi described in BitDNS. But that doesn't disprove satoshi's involvement in Namecoin. (again, I have no proof that he was involved, just that some of the general approach he described for BitDNS found its way into NMC.)
Satoshi himself made several changes to the codebase of early versions of Bitcoin; most likely because it was pointed out to him that there was a more efficient way of doing things than he originally intended. So its not a far stretch to assume that just because he said something should be one way at one point, it doesn't mean he couldn't change his mind about it later.
In case of NameCoin, they have their own difficulty. They trace only 80-byte headers, which are submitted to their network. Which means, that you can do 51% attack on NameCoin, even if you can't do 51% attack on Bitcoin, with the same hashrate.
In theory, but its never happened as NMC has a hashrate of about 50% of BTC, which makes it ungodly secure compared to any other SHA256 coin (aside from BTC). For reference, NMC is about 470 EH/s while BCH is about 3.3 EH/s. There was a risk of a 51% attack in 2016 due to mining pool centralization. It was also
threatened as early as 2011, before the implementation of merged mining.
In any case, I said upfront that it was a conspiracy theory - not even just a run-of-the-mill "theory" - its just something I'd heard others claim in the past.