Yes, the First amendment to the Constitution guarantees the right to free speech. You are free to expound on any message that strikes your fancy. You are not free to spray paint your message on my house.

You can complain that Google's political ideology may cause them to selectively enforce their stated policy. Any complaints that it is censorship because they won't publish messages that you like are specious. Censorship implies that force is being used to prohibit some entity from distributing their message. Just because Google doesn't allow someone to spray paint a particular message on their house doesn't make it censorship.