I can feel the way the wind is blowing. Sooner, rather than later, the word "debatable" will come to mean "amenable to rational discussion", or "willing to debate", rather than, as now, "a matter of opinion" or "open to dispute". It may well happen in our lifetime.
Robert Spencer, in an otherwise very well-written post - all his posts are well-written - uses "debate" as a transitive verb to refer to his potential opponent, rather than to the topic:
I would, of course, be happy to debate any scholar about Islam and jihad; this is a standing invitation." In reality, several Islamic apologists have recently approached me with challenges to debate, and I've told them I'm willing to debate them all.
I would say not "debate any scholar about Islam" but "debate Islam with any scholar". You debate a subject, but you debate it with a person.
As with "impact", however, the tide is turning. If I were an American, or a Briton who would be under thirty in twenty years' time, I would think it perfectly acceptable to use "debate" in this way. And I would be right. That's how it goes. So if a man can be "debated", that is "argued with", in all his new-fangled transitiveness, then he is "debatable". How can he not be?
Interestingly - to me, anyway - "debatable" is one of the definitions of "problematic". But for how much longer? Language change impacts us all.
'Come live with me and be my love,' He said, in substance. 'There's no vine We will not pluck the clusters of, Or grape we will not turn to wine.' It's autumn of their second year. Now he, in seasonal pursuit, With rich and modulated cheer, Brings home the festive purple fruit; And she, by passion once demented --That woman out of Botticelli-- She brews and bottles, unfermented, The stupid and abiding jelly.