Besides if the Tauthon people are serious about maintaining their fork long term it needs to become more than a mere fork and a real language ecosystem of its own, in the long run having a different name will probably help with that, assuming that they ever get there.
EDIT: Also reading the rest of the thread I realize that the post that you linked out of context is slightly misleading (but I blame github's aggressive folding more than you here). Guido's answer comes after the following exchange:
stefantalpalaru: "Disregard Guido's objection. The "Python" trademark doesn't extend to "py2" or "py28". Read this for details: https://www.python.org/psf/trademarks/"
Guido: "Isn't the whole point that we're trying to solve this without lawyers?"
stefantalpalaru: "The whole point is that you've been sabotaging Python 2 for years and when someone does what needed to be done from the start, you come up with silly objections."
Guido: "OK, bring in the lawyers."
In that light, and given the other poster's ridiculously inflammatory take, Guido's answer seems rather level headed and appropriate IMO. He stands his ground, so to speak.
Please note that Perl 6 has been renamed to Raku (https://raku.org using the #rakulang tag on social media). So Perl and Raku are now considered to be different languages, albeit from the same inspiration.
Now, if Python 2 people would decide to rename Python 2 to something else, I guess it would be a mirrored parallel :-)
It's not a mirrored parallel, it's the Python folks learning from Perl's mistakes and making sure that this parallel won't come to be.