True but I'd assume they'd still have to hire a lot of developers because some people for one reason or another wouldn't or couldn't leave their current occupation at MercurySteam. Also by creating a new studio, you lose all the technology developed at MercurySteam from Samus Returns and Dread which means rebuilding a pipeline from scratch or using an engine like UE4 that'd require a lot of customization to get performance right.
On the other hand I could imagine a Nintendo owned studio in Spain attracting a lot of people (especially if Nintendo applies the same quality of work environment they apply to other regions of the world).
And this is without mentioning finding a good spot building wise and get into constructions. I also have no idea how the Spanish government would react to a Japanese corporation like Nintendo funding a big company capable of disrupting the current market for videogame development.
I seem to be jumping around in an incredibly disorganized fashion -- so it goes -- but this post just got a response, so I might as well mention this while you're getting notified anyway.
Having to hire a lot of developers? Not having access to MercurySteam technology? Finding a good spot for a building? Dealing with construction?
These are problems for Nintendo to solve, and they're likely in a better position to overcome these hurdles than an underpaid collective of developers making an exodus from MercurySteam would be. These exact problems are why it might make more sense for Nintendo to start a studio and bring in these developers than it does for the developers to strike off on their own -- as these hurdles are likely why individuals facing the conditions put forth in the AnaitGames article wouldn't have struck out on their own as is.
If we assume that Nintendo won't or can't buy MercurySteam to reform it, and we assume that the ongoing issues are MercurySteam's problems to fix themselves -- but that, given their current reputation, previous reports along these lines, characterization of people in charge, lack of progress on this front so far, and so forth --, and we assume that the developers aren't equipped to overcome the hurdles you mention -- which, maybe they could --, then the options are status quo versus a new Nintendo studio (or studio started by some other entity).
If we start with these assumptions -- which you don't have to, and I'd be interested in hearing that perspective -- then putting these hurdles forward as a valid reason this new studio shouldn't be formed is a vote for the status quo.
As for disrupting the current Spanish market for videogame development, might it not be a disruption for the better? Could it be seen as creating a market more people will want to join?
[Edit:] That's not to say Nintendo or any other entity wouldn't see those as reasons to refrain from starting a new studio there as described. They very well might. It's not even unlikely. But leaving things as-is would be unfortunate.