This is a real dick move on their part. There are quite a few gun manufacturers (Armalite, SIG, Walther, etc.) that actually sell officially licensed airsoft versions of their products
on their official web sites.
But anyway, if they're only suing distributors (and many airsoft retailers that sell to Americans aren't actually based in the U.S.), it won't make a difference. The only thing they're going to is alienate 90% of their fans.