OSI, and the open source definition they produced, predate the very notion of public cloud by close to a decade. While you don’t have to accept the definition, you are out of step with the industry at large, who broadly use “open source” to refer to things which meet the OSI definition. There’s no need for a competing definition: it’s fine for software to not be open source.
As to the specifics of SSPL, I personally don’t see the rationale for accepting AGPL but not SSPL.
At large? As you can see, there is room for a community with a different view on that. My personal definition of an "open source license" is that, as the name implies, I can access the code, preferably without much gatekeeping (e.g., creating a free account in a private GitLab instance). And, to be honest, I prefer the BSL with an Additional Use Grant over any other license, because this is the most reliable option to ensure that the project has a future and won’t be abandoned because no one wants to invest their time for free.
You are welcome to choose that, but in my opinion, it isn't open source. I think open source should means anyone can contribute or take, and contributions are shared, without undue discrimination. Nobody is forced to work on the project, but if they are then they have to give the results of their work back to the common pool they took from. You have just as much power to keep the project going as anyone else does, including the current "maintainer".
As to the specifics of SSPL, I personally don’t see the rationale for accepting AGPL but not SSPL.