If you have a trademark, you have to defend it, or you risk losing it. Is it ridiculous? Yes. Is it incomprehensible to an outsider? Yes. Nevertheless, it's par for the course.
Only if your trade mark become a generic symbol is there any chance to lose it, and only if it is your trademark or something super similar and not something distantly similar.
I.e. this is just bulling and nothing more, Apple's only potential benefit is to try to deter other companies from ever using logos based on Apple's or peaches, which would be a cost abuse of power (even if legal). Oh, it they plan to bring it a similar app and try to hampper competition, which again would be abusive behavior.
But risc to their trade mark never did exist because that (or more or less any other) pear trade mark!
edit: it appears that Apple lawyers never tasted pears and think it's the same thing