I don’t agree.
Your second paragraph is true, yes. Though, I’d frame it more around ‘health’ than ‘weight’. I’m not saying ‘weight’ has no impact on health, but the health is the important part of the equation to focus on (and, even there, ‘health’ can be a dog-whistle for fatphobia sometimes). It’s that focus of ‘fat=bad’ that is the ‘concern trolling’. You don’t need to ‘fix fatness’, you need to fix all those other problems.
Its not a ‘poisoned well’ if someone is telling people their weight needs to be fixed pisses people off (even if it’s framed as not their fault!), and it is understandable that others find such comments to read as concern trolling.
Disagree, that’s not what hard science means, nor can it be isolated in such a way for a lot of people.