My roommate put a political sign in our shared window without asking

I came home Monday and found a large campaign sign taped inside our living-room window. It faces the street and is visible from the bus stop. My roommate was pleased with it. I was not.

This is not because I support the opposing candidate. I have not decided how I am voting, and even if I had, the problem would be the same. The window belongs to both of us. Anyone who sees the sign will reasonably assume the apartment is making a statement, not one bedroom.

When I asked him to move it to his room, he said political expression is not something roommates get to veto. I said shared display space is always negotiated; he would not want me hanging a business advertisement or a religious banner there without asking. He replied that an election is different because silence also communicates something. That sentence has been circling my head because it turns every undecorated surface into an accusation.

There are practical complications. Our lease has a general clause about window displays, though I have not asked management how it applies and do not want to manufacture a legal threat. We also live on the ground floor. I do not love advertising our political preferences to strangers or to clients who occasionally drop off materials for my roommate's freelance work. He thinks those concerns are exaggerated.

I offered three options: keep the sign in his bedroom window, put it on a removable stand outside only while he is home if the property rules allow it, or agree that either roommate may use half the shared window. The last option was sarcastic and not especially helpful. He heard all three as me trying to make his support invisible.

What is the fair default for political signs in a shared home? Does one resident's wish to speak outweigh another resident's wish not to be represented, or should shared-facing space require two yeses?