People who are incensed at an injustice done to them and their loved ones aren't given to carefully parsing a country's foreign policy. It's guilt by association- which is the same judgment Western nations use when they bomb and invade a Muslim nation.

Still, there's plenty of responsibility to assign to both Germany and Belgium. They're both members of NATO, and took roles in NATO's warmaking in Muslim lands. Sweden isn't a member of NATO, and as far as I know has never made war in a Muslim nation. But Sweden is of course a close ally of the Western nations that do kill Muslims, and it doesn't condemn those acts.