Regarding freedom of speech, the United States does have the concept more strongly encoded in law than the other 3. China's Constitution has Article 35, but apparently there is little enforcement of these rights (http://www.rfa.org/english/news/china/constitution-day-prote...), so such is toothless. I am not aware of a freedom of speech law in Iran, nor I was able to Google one.
Malaysia does have freedom of speech protections with Article 10. Having said that, the legalese is not as strong as the US's Amendment 1 -- the Sedition Act overrules Article 10, for instance. So criticizing the leader in Malaysia could bring you into legal trouble, unlike in the United States.
The First Amendment is not completely unbounded either, but unless you can demonstrate a US equivalent to Malaysia's Sedition Act (Malaysia being the country with the strongest freedom of speech protections of the three being compared), well, I think the OP has a point.