Because the gp comment is not about grapheneos, but its creator and could be taken as insulting (considering none of them is likely to be actually schizophrene).
There's a few things to unpack here from my point-of-view.
First, I didn't see him calling any person schizophrenic. I don't follow the Android scene so to me GrapheneOS seems like an organisation rather than a person.
Legit question, from a clueless person. Please be gentle! :)