If you support taxes (or striking) and the government (or the union) forces you to pay taxes (or strike), you're not being "forced". So far so good. But what if you don't support taxes (or striking)? You might think taxes are a good thing and are necessary for a functioning society, but it's still pretty clear that for someone that doesn't want to pay taxes, they're forced to pay taxes.
Saying something isn't "forced" is the opposite of "overloading the string "forced" with several meanings". Also, in the broader context of this argument, I'm for an more expansive definition of "forced" and replying to someone who thinks whatever the union is doing isn't "forcing" anyone. Therefore I'm actually granting my opponent some leeway. If you think the above circumstance also counts as "forced", that actually supports my claim that whatever the union is doing is "forcing" people.
I'm under the impression that the strikes are being enforced by the union. In other words if you're a union member, and the union voted to strike, you can't unilaterally decide to continue working. Is this not the case?
How would that work with basic human rights such as the freedom of association? And how could it be enforced, under civil law?
Of course you are free to break the strike or whatever feels right for you. But it might not be compatible with membership in the union, so they may well exercise their right to not keep you around as a member if you are actively trying to sabotage their work.
You can work, you can't be part of the union. Not being a member doesn't remove any benefits the union might negotiate with the employer, you just don't have access to the perks of the union (higher income insurance is usually the most important one).
I suggest learning more about the Swedish model before spouting opinions on how things work here, you don't understand the system but feels entitled to argue on your assumptions.