There isn't a way to determine, via the API, if a particular user is blocked from editing a specific page.
This means any implementations of UserIsBlockedFrom is ignored and the client will assume the user cannot edit a page they may be able to edit (i.e. the client will assume a site-wide block). While the user will be notified that they are blocked (and the client will prevent editing) the actual edit request will succeed.
Add to ApiQueryInfo an inprop to indicate whether the current user is blocked from the page. This should execute User::isBlockedFrom.