You may think people foolish for going there, but that still doesn’t mean that their purpose for doing so was to protest (as you originally stated).
You are correct.
As an aside, many Russians who agreed with the revolution in 1917 and wanted communism to succeed returned to Russia. The nature of ultra-authoritarian regimes is inherent paranoia. If you’ve been out of the country and especially if you’ve obtained citizenship in another country, you should be thinking about how that regime is going to view you. History records that the communists killed every single person who returned from abroad.
When it comes to ultra-authoritarianism the Iranians are much more so than the communists. I’ve known people who went back into somewhat similar circumstances from America and into Hell. Their attitude is they KNOW they aren’t dangerous to anyone. What they fail to take into account is that the opinion that matters belongs to someone else.
Then there’s the tendency of low-ranking people in a regime to create issues they solve so they get noticed. I’d wager there are secret service people in Iran making arrests of “spies” if only to develop a reputation, so they get promoted. They don’t give a hoot that the people they are arresting and executing are just ordinary adult children returning to care for elderly parents, or similar.