I don't know how casting an Asian person is somehow offensive to the Chinese. This might be a case of Marvel addressing a sensitive issue without really understanding if it's a concern for the audience. There are a dozen ways to have cast an Asian and made things more vague if the concern was really China vs. Tibet.
You don't know how casting an Asian person is somehow offensive because you haven't rigorously studied the issue. Disney has poured probably hundreds of thousands of dollars into market research on casting, and thus THEY KNOW exactly how casting an Asian person in this role is offensive. They know in excruciating detail. They have reams of spreadsheets detailing projected losses for every possible casting scenario. Disney doesn't do things half-assed.
For us to speculate on what is or isn't offensive is silly, honestly. We have no idea.