Yes, this is a tactic by Ryanair to get things done how they want. So maybe they would have reduced London to Malmo (for example) anyway, but they are right to use every opportunity to denounce this tax. It's their obligation as an airline!
There will still be the same amount of aircraft based in Skavsta so the staffing requirements in Sweden are practically the same.
It's aircraft that are coming from other bases such as Dublin and Prestwick that will be operating reduced services to Sweden. These aircraft WILL be put to other use, so the staffing requirement for them remains unchanged also.
i.e. To suggest that pulling out of Sweden is to mask understaffing is ridiculous. It's just not the situation.
And a 7 euro increase in the price of every ticket is WHOPPING! and would / will have a huge impact. I regularly fly from Ireland to Charelroi. Mostly I choose Shannon because my ticket typically costs 10 euro cheaper, due to differences in airport charges.
If you are organising a stag night or a golfing trip for a group, then you are going to price a whole series of potential destinations with cheap tickets. You'll be a whole lot less likely to choose Sweden because of the airfare.