This is basically correct. But there is one crucial parameter missing; namely how much of that meat or animal products can we safely eat. Even great apes rarely consume more than 10% of their callories in animal foods (most likely insects) which aligns surprisingly well with findings of dr. Colin Campbell. Anything above 5-10% will start causing or contributing to chronic diseases we see today. 5-10% means one fish per week or one steak per fortnight at best.

For those who are not willing to do some homework in plant nutrients, vegan+fish is a safe option. But with a little bit of effort you can replace fish with flax seeds, wallnuts, dried algae (...) and thus help yourself and the planet a little further.