nice strawman you've got there. people doing keto get harassed far more often about the bogus health implications of saturated fat. Shit I doubt the average person has ever even heard of anti-nutrients or thought twice about the nutritional value of plants beyond their prominent place in the antiquated food pyramid. but they know for a fact, duur fat=heart atak
Okay, but you do know that eating nothing but meat is bad for you? And eating buttloads of butter is not healthy? And vegetables have consistently proven health benefits?
There are insanely unhealthy versions of pretty much any diet. I know plenty of vegans who gain weight because they end up chasing the same bad eating habits in plant form. Eating excessive amounts of fruit can still qualify you as a vegan but it won't change the fact that you are on the fast track to diabetes. The dirtiest forms of dirty keto can lead to insane consumption of artificial sweetness or natural sugar substitutes which are riddled with their own health risks.
That said... Veganism and really vegetarianism to some degree is still a diet that people still seek for non-dietary motivations, and pretty much any restrictive diet is going to require a degree of finesse and knowledge to make sure that diet will be nutritionally sound. It's not out of bounds to be concerned about someone you care about in those terms.
Okay, but you do know that keto includes plenty of vegetables and is not "nothing but meat"? Spinach, broccoli, bell peppers, cucumbers, salad, asparagus, olives, eggplants, avocadoes etc