there are no 0.5 nodes at all on the Bitcoin network, that's zero precisely.
I wouldn't be so sure about that part. I distinctly recall some of MP's fervent disciples openly encouraging client spoofing as a means to derail support for XT. It's unlikely they're displaying their actual software version. It's not difficult to change. And it makes sense if you're an extremist who wants to stay under the radar. I'd agree there probably aren't many "0.5.4." nodes running, but I suspect it's more than zero.
Well, if you want to continue along these lines, consider something else.
Bitcoin version 0.5 would take a very, very long time to download & verify the full Bitcoin blockchain in 2018, probably several months (0.5 didn't even use a UTXO set, every block would need to have every transaction validated by seeking back to the block that every output was spent from). Anyone trying to switch to 0.5.4 using their current blockdata would find it doesn't work, unless all the latest un-Satoshisms have been backported to it (which would make the whole concept that little bit more ridiculous), this vaunted hard fork attack couldn't take place using 0.5 era software even if someone wanted to do it (
no takers so far on all the "vulnerable" P2SH addresses, which only contain BTC 4.3 MILLION at this point in time, but of course the Schelling point hasn't been reached yet, 4.3 million BTC isn't worth it, lol)
If it's completely impractical to sync a "Satoshi immutable" node, how many people could really be a part of this regressionist hard fork movement that's the Bitcoin equivalent of a 19th century steam driven car? It's a very bad joke
So, I am "so sure about that part". What reason have you got to believe any of this nonsense?