You can’t sue somebody just because there’s no proof they aren’t out to get you. You need proof even to file a complaint - lawsuits aren’t fishing expeditions.
And all the evidence here is that apple simply doesn’t have the resources to prevent every clone. In fact, they aren’t even obligated to. Unless the clone is a copyright or trademark infringement, or does something malicious (e.g. it doesn’t perform the functions it claims to, or it violates an App Store policy), then there is no problem with clones, no matter how similar they are to the original app. In other words, when the complaint complains about apple allowing “similar, inferior” apps, so what? Isn’t that the competition you crave?
If these apps are really “scam competitors” in the sense they are ripping off customers, then they need to be removed. But, again, the fact that they made it into the store in the first place doesn’t show that apple has animus against this developer - in this thread alone there are posts from other developers that happened to.