The term "more unwarrantable" refers to something that is even more unjustified or without proper basis. Antonyms for this word could include "justifiable," "defensible," "valid," or "reasonable." These words indicate that there is a basis or reason for something and that it is founded on facts or logic. Alternatively, antonyms for "more unwarrantable" could include "warranted," "authorized," or "permissible." These words indicate that something is justified or allowed based on some sort of authority or permission. In either case, the antonyms for "more unwarrantable" suggest a sense of legitimacy or justification that is lacking in the original term.