I think she is not criticizing people for being homesick.

Rather, she is trying to say that many Chinese criticize the countries that host them, while enjoying all the benefits there. They do not tolerate others to criticize China to the same degree.

Everybody goes wherever her/his best opportunity is. By staying overseas for life or many years, she/he demonstrates to the world that she/he has chosen another country over China.

All arguments, no matter how loud or beautiful, are pale compared to facts and truth.

Truth and love, they will lead to peace, my friends.
I