Poor Buddy. You have to realize that he has gone from one extreme to another. First he was an outside cat, then had to adjust to being an inside cat and then got the taste of freedom again. It has to be hard on him also. I know it is also annoying to you and your family, as I have been through it myself.

There are a few things you can do. If you do not want him out at all, then when he starts his whinning, squirt him with a water bottle and firmly tell him NO. Gradually he will learn.

You can also make a safe cat run for him, which i'm sure he will enjoy, or you can gradually train him on a harness and leash for outings.

Which ever you decide, I wish you the best of luck with the situation.