"The First Amendment guarantees freedoms concerning religion, expression, assembly, and the right to petition. ... It guarantees freedom of expression by prohibiting Congress from restricting the press or the rights of individuals to speak freely."
Freedom of speech does not protect you from harming others directly (yelling "bomb" on an airplane is not protected). But the issue with HK and China is -entirely- what the first amendment is trying to protect (albeit usually this is usually to protect Americans to complain about America).
When Americans see an American company denying someone what we perceive as an unalienable right it becomes infuriating.