The app store essentially has a monopoly on selling apps to Apple devices (I'm not sure whether Cydia is legal over here; besides jailbreaking hardly constitutes a reasonable alternative regardless). In what other market sphere would a manufacturer of a product be able to control what you use a product for/what you use it with. If Apple (or Microsoft or Google or anyone else) are taking that approach then the grounds on which they can reject apps should be severely limited.
Apple wouldn't be allowed to cream a commission from every Amazon purchase made using Safari (either on iOS, OSX or Windows) - this is essentially the same as that.
And bearing in mind that Apple's market share of the smartphone market is around the 50% mark it may not be a monopoly but it's enough to require strong regulation.
Jailbreaking voids your warranty. I think that could be considered coercion...
I'm sure the SkyDrive team can detect an ios browser and hide that link...
I'm sure they could. But should they have to? Imagine you only encounter SkyDrive through iOS and fill up your storage. You'd never know you could buy more. And if you did you'd have to manually visit the website to do so. As I pointed out above this is no different to Apple demanding a commission for every Amazon or eBay sale made through iOS.
Anyway, if you mean the link to subscribe, that wouldn't be good enough for Apple (if you mean the link to sign up that would just be stupid - it would massively break the UX for any new users):
Microsoft has persisted in trying to work out a compromise with Apple, but has thus far failed to come to an agreement. The company offered to remove all subscription options from its application, leaving it a non-revenue generating experience on iOS. The offer was rebuffed.
EDIT: Dropbox removed their sign up link. Yay for broken user experiences...