Is it acceptable to say that a reviewer's concern is not going to be addressed because then the paper would be too long?
This is the kind of thing you ask the editor about. "If I include this philosopher's view, the manuscript's length will increase by roughly 40%. Are you sure?" If the editor says yes, you're in the clear - they are clearly going to waive the word limit. If the editor says nevermind, you're also in the clear - even if the reviewer objects, the editor's on your side and can overrule the reviewer's objections if the reviewer recommends reject.