That's the right wing nuts claiming that.
While the news was reported by both InfoWars and ZeroHedge, Facebook denies that is the case.
According to a Facebook spokesperson, posts that with the phrase “honk” in them that may have been flagged contained some other troubling behavior patterns the site bans, such as images that may have involved “organized hate.”
By the way the first amendment free speech rights applies to government laws, not twitter, facebook and geese.
The First Amendment (Amendment I) to the United States Constitution prevents the government from making laws which respect an establishment of religion, prohibit the free exercise of religion, or abridge the freedom of speech, the freedom of the press...
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.