What are his objections to your owning a dog now that are alleviated with a foster animal?

It sounds from your post that he's concerned about the condo (I'm assuming size and lack of yard) and your work schedule.

A foster animal is NOT the solution to these issues. Most of them have issues of varying degree and need far more attention than a dog you own that is comfortable in your house, etc. It's a rewarding, but sometimes heartwrenching, experience; however, if you don't have the time, space, or commitment to a full time pet chances are you don't have the time, space, or commitment for a foster animal even if it is supposed to be shorter term. They just need work.

Find the dog that is right for your living situation and enjoy him/her IMO.

Fostering is a great experience if you have the time and stability to do it, but you do need the time.