Rejected posts are controlled on Google's end and not Social Marketing.
"Typically posts are rejected due to content or because of the photo/image being used or if your business is in a “sensitive” topics area.
Sometimes words within the post will trigger a post rejection. The word may seem benign, but it may be on Google’s “offensive” word list.
If your post gets rejected, try re-wording to a more generic body copy, and don’t include any sensitive words or images.
Also, it used to be acceptable to include your phone number or a website URL in the body of a post. Google is now rejecting many posts with phone numbers or URLs.
So if your post is rejected, try taking those elements out"
Google Posts are also not permitted for multi-location chain businesses.