I've essentially already answered this in my previous post, but for clarity...
Yes, I as a Solo player could use a bigger carrier than an FC. I had to clear out stored cargo to make space with the Colonisation update because I didn't have room.
By your logic, the minimum number for an SC should then be 2 players, because that's how many would be required to take full advantage of the bank feature.
For players that are storing up Billions of credits "more grind" isn't a thing. We're already "grinding" (playing the game) more than the game requires. What we are looking for is more things to spend it on.
On the point of more storage, keep in mind, this is a circle: you get more cargo. So colonisation becomes too fast. So they have to increase costs for colonisation. So you need a bigger carrier. In my eye, not the direction we should be going for.
And by my logic, indeed... anything less than two is a pure ridicule of a "squadron carrier". And even two, in my eyes, defeats the purpose. The game has a lot of solo content. Squadrons by name and meaning are group content. If this thing i not oriented for groups, then it does not need to exist.
Sure, the part with perks, that can require some finetuning still. But the squadron carrier, they failed on the first try, and made it a solo-carrier. They should not fail another time.