He's saying such a rule from the EU could allow spam from the companies themselves, not that these posts from advocate users would be an instance of spam.
> He’s saying such a rule from the EU could allow spam from the companies themselves
The word “consumer” in the rule that gatekeeper platforms must not “prevent consumers from linking up to businesses outside their platforms” has a meaning, and that meaning is, in this case, “Elon Musk is wrong”.