I've never canned garlic scapes, only made refrigerator pickles from them. However, I think nearly anything can be pickled, or at least it seems like that.

My only concern would be that the garlic scapes have a different texture, they are not as tender or porous as some other vegetables like cucumbers. I also note that approved recipes for harder vegetables like pickled beets or carrots have a greater proportion of vinegar to water, so if I were going to can the pickled garlic scapes I'd be more likely to choose one of those recipes as my "base".

That still won't make it approved or tested, of course, so only you can decide if the risk is worth the reward!

Annie