The % that’s edible is not as relevant as the fact that it still takes much more human-edible feed

Not really. Definitely not if you consider the nutritional quality of the meat. And that's beef, the worst example. (Feed to meat conversion from 6x to 25x, the higher number generally for free-range). Chickens are only x2 in ideal situations (closer to 5x when free-range since their calorie intake is not as well-managed). And from a health viewpoint, 100kcal of chicken is a better-balanced calorie than 200kcal of feed

But that is before accounting for the fact that about 165 of those feed kcals are inedible, meaning you're trading around 35 edible kcals of corn for 100 edible kcals of chicken. Would you agree from a purely health and efficiency point of view (leaving out ethics), that 35 edible calories of a "non-nutritional grain" for 100 edible calories of a protein superfood is a pretty fair trade?

Synthetic fertilizer usage is greatly reduced by eating plants directly even compared to the best-case use of animal manure

Missed this one, so jumping back. It's hard for me to respond because I don't have access to the whole paper. There seem to be fairly significant issues with it, however. For one, I can't find any corroboration that isn't merely citing this paper. For another, I can't find any critical responses either (the lack of them is worse than a half-decent one IMO). Nonetheless, there's a few things I find interesting from the summary the seem to make it hard to just accept an argument using it

1. The killer, to me. This paper actively presumes that all crop farms that produce crops that have inedible components that cows will eat (like corn) will pivot to 100% vegetable. But a vast majority of that crop's output is in explicit demand and corn farms are not just going to fold up. They will start destroying their excess waste instead of reselling it as feed. That ruins his math. But he also failed to take into account what a world horticulture setup would look like that actually sustains humanity, and merely counting IFE is just not enough.
2. This paper seems to claim a 65% reduction in fertilizer usage, but doesn't account for the fact it would HAVE to primarily be synthetic fertilizer if we stopped eating cows. This is a huge problem for me because I'm an outspoken advocate of collaborative farming, to reduce the disgusting use of synthetic fertilizer by regulating and enforcing better use of manure and localization of animal farms. There's far more than 3x as many cows in the world than can be maintained if they aren't being consumed. He does not cite or comment on how much worse synthetic fertilizer is than manure fertilizer. And if I'm reading right, that's his high end. It might only be more like 30%. I would rather 100 units of manure used than 70 units of synthetic fertilizer without a second thought.

And your second link... I'm not sure why you cited it. It appears to be arguing for my side, defending the figures I used. Thank you?