Spam is "bulk mailing of commercial and other advertising or similar commercial messages to individuals who did not Express a desire to receive".
The definition is too specific and not related to this case.
There was not like this. It was ordinary communication. Is this spam?
The real definition of SPAM is:
irrelevant or unsolicited messages sent over the Internet, typically to a large number of users, for the purposes of advertising, phishing, spreading malware, etc.
Which applies to your "friend" or "coworker" who was shit posting.