Well, he will certainly quickly find out whether the women he is interested in dating likes dogs or not, which is all to the good from his point of view.
From your daughter's, you can judge a lot about a person from the way they treat their pets. If the dog makes a nusiance of itself, she probably won't want to continue seeing this man. Ditto if he swears, shouts or sounds angry, when he addresses the dog, or if the dog seems cowed.
In the past when I dated and now when inviting people for the first time, I always ask if they are allergic to, or dislike cats, as I have two. I wouldn't want anyone to become ill by coming here unaware of my cats.
By mentioning that he would like to bring the dog, he signaled that anyone afraid of or allergic to dogs might reasonably want to back out.