"Is there a policy here that if you do not use your full name on a post, your post may be removed?"
"may" is the operative word.
Yes it has happened plenty of times and it will happen again.
If a poster is known to the regular readership under whatever pseudonym he uses then that is ok, but when a new person appears making a sales post, readers will want to know who they are dealing with.

If and when the "may" happens can depend on things such as whether Greg enjoyed his breakfast