When I first saw SaaSS I figured RMS had his own acronym for SaaS, and sure enough further in the article he spells it out - Service as a Software Substitute.
I think it detracts from his message when he uses these derogatory nicknames in anything other than in introduction. Like when he's talking about the "Swindle" (kindle), he will refer to it that way throughout the entire article, rather than just make a point an move on.
Services are offered in substitute for software precisely because IP has become socially, legally, and technically impossible to protect, so the only way to protect it is to put it behind an API gate, which (ironically) offers far less Freedom than any copy of Windows ever did.
After all, your copy of Windows never forced deprecation of API functionality you wanted to use.
There are cases where the service is not substituting software. E.g., something like Stripe or Twilio... versus software which is offered as a service because it's a nice form of DRM.
It seems to me that people rarely think about the software behind a service, this is a mechanism to bring that secret software into people's minds and discussions.
I like it!