Is my employer allowed to tell anyone that i work with why i was fired.

Interesting issue. Were charges filed and was he convicted? If so, I suspect he's lost a lot of room to complain. If not, the charges, while they may be inaccurate, have not yet been proven in a court of law. In that case, employment privacy is generally pretty strict. You should check with your state EEOC office and see what rights you have there.

I would call an attorney if the allegations weren't proven, as this may be a case of defamation of character. If he did however steal from them, then I don't know if they should have listed that they were fired but I could see posting their names and faces so that others would be aware that they are criminals. In that respect, it is in a business owners rights to do that.
There are no federal statutes forbidding employers from saying what they want about former employees. State laws prohibit defamation (slander and libel), which is broadcasting false info about a person when the communication is not privileged. Honestly reporting that someone was fired can't be slander. Honestly reporting that someone was fired for theft or absenteeism (etc.) can't be defamation either.
Contrary to popular belief, employers may speak candidly about the reasons they fired employees, including when potential employers conduct employment background checks.
Hope this helps. Susu