As a Veteran, still serving after 8 years, I love our rights. And yes, you do have the right to free speech- there are caveats
They have a disclaimer discouraging it, you said so yourself (however, it is forbidden, as per their rules). Also, your particiaption is presumably based on a freely-entered-into agreement that gives them the right to do this, even if it is seems unreasonable or you feel it effects your right to free speech- you agreed to the TOS.
This was taken from their TOS page
"The HiTech Creations Service provides you access to the multiplayer game Aces High™ and their associated message board. "
"6. Either you or HiTech Creations may terminate your HiTech Creations membership at any time, with or without cause."
And this was taken from their General Discussions Forum rules
"14- Posting topics or threads which are based on politics, race, or religion is expressly forbidden."