I never use any form of the word "poly" when I first tell someone about me. I talk about exclusivity and non-exclusivity, and if the convo continues, I mention "cultivating multiple committed loving relationships." I have been surprised that several guys do know the word poly, but yes, I still had to explain to some that it does not preclude love and commitment.
If there was any mistake made, perhaps this should have been brought up much earlier, during your texting, etc., to make sure he understood before meeting you, what you are into. Ah well, maybe you can still get through to him, maybe not. Consider it a learning experience and move on!