Going by the other stuff that individual wrote? Yes, they very much were saying that without alignment written out, they could just interpret anything any way they want, because everything is "now subjective."
Also, removing the alignment from the stat blocks, leaves monsters like the Relentless Killer (Page 242) without guidance on its moral outlook The text just says Relentless killers are hateful, revenge obsessed creatures.
Yet, by skipping alignment in the stat block, nothing to say if the above are lawfully good actions. Basically, 5e since Tasha's encourages all rules to be read subjectively.
The good news is that no more rules lawyers arguments. Everything is subjective now, and even that Relentless Killer could basically be a lawful good paladin in training, if your table so chooses.
Maybe they were being facetious, but it really seems that they relied on alignment to determine a creature's moral outlook.