> Would they not be allowed to use their expertise to develop and like system without violating the existing patent?

Maybe, but that's kinda the point of this lawsuit. As Apple implemented it, they did violate portions of the patent. Not every part of their claim was considered a violation, but some of it certainly was:

> As a result, the Commission finds that Apple has violated section 337 as to claims 22 and 28 of the ’502 patent and claims 12, 24, and 30 of the ’648 patent.

https://www.usitc.gov/system/files?file=secretary/fed_reg_no...