It's true, it's difficult to judge how people will take your wording. I took his words as the opposite--possible mate meaning that he is studying and wants to make sure it will work out--the 'possible' meaning he may not even allow them to breed! Sounded like he was being responsible, as opposed to being automatically determined to have puppies.
But that's a forum for you, lots of misunderstandings can happen! That's why I always like to double check and ask people just in case I am misreading them XD