it’s actually impossible to have an unarmed interstellar spaceship

Since this subthread had already stepped into the realm of sidetracked internet debate, I’d like to challenge that claim.

I understand that the reasoning behind this statement is that interstellar travel requires some properties that disqualify the ship from being considered “unarmed”:

• Interstellar travel requires ridiculous speed, which makes the ship itself a kinetic weapon.
• The ship will need formidable defensive mechanism to survive cosmic radiation and impact with particles at the speed it is traveling.

I see two problems with this argument:

1. The spaceship could use some sort of FTL travel, which may or may not bypass these requirements entirely.
2. Regular cars have enough kinetic energy to kill people, and they are reinforced to a certain degree so that they won’t break from the strains of the speeds they travel in. Would you also say that it is impossible to have an unarmed car? One could certainly make such a claim, but that kind of drains the meaning out of the term “unarmed”…