If you want to get an idea of the timing of which Link needs to be in hitstun for in order to let the Gale travel past him. Throw the boomerang, pull out a bomb, then down throw as the gale is returning.
That's the timing for which the gale needs to return before Link is thrown.
So examples of throws that have long start ups this would work on, would be:
Rosa's Back Throw
Ness's Back Throw
Mario's Back Throw
Mewtwo's Up Throw
Sadly this is too situational to be used effectively. Because it works only when Link is put into hitstun, you need to rely on stage positioning near the ledge, your opponent to throw you before the gale returns, and then the gale sweeping them off the stage as their throw animation is starting up. Making this too unreliable and unsafe to be consistently performed (if at all).
Edit: I did more testing and actually found another way Gale releasing could work.
So essentially there are two ways to perform it:
Both methods have to be near the ledge in order to work
>Grabber is closer to the ledge
>Link is closer to the ledge
As previously mentioned, if the grabber is closer to the ledge, the gale return has to be perfect in order to sweep them off the stage and force a grab release. Although very hard to perform, it puts Link in a good position to punish accordingly.
However if Link is closer to the ledge, the gale's windbox will come in contact with the grabber first, pulling them forward off the stage and forcing a grab release. This method is much easier to do, because as long as the gale doesn't come in contact with Link first, the windbox will be intact. But it will always result in Link being pulled offstage, which will result in loss of stage control, as well as putting Link at a disadvantageous position against characters with good off-stage games.