Do the Rohingya have a right to defend themselves through armed resistance?
Of course; but that is irrelevant. The Rohingya have many rights that they can’t exercise, and armed resistance is one of them. They have the right to freedom of movement, but can’t move freely. They have rights to education, work, representation, the right to marry, and so on; but these rights are denied by the might of the government and the army. The right to resist through armed struggle is also prevented by the might of the government and the army.
Look, any time you are denied your rights, you are not literally incapable of trying to exercise them; you are not preemptively prevented. You can do as you like, but you will be punished for your attempt, and knowing that you will be punished stops you from doing as you like. And if the threat of punishment does not stop you, and you attempt to exercise your rights, then you will face the power of those who want to prevent you, and your attempt will fail. You have the right, but you do not have the capability to exercise your right. You are overpowered.
When I was in prison, I decided to leave. I was prevented.
Almost half the entire Rohingya population has fled Rakhine state because it turns out that the might of the government and the army is greater than the might of a couple hundred guys with machetes, farm tools, and a few confiscated guns who decided to exercise their right to armed resistance without having the capacity to succeed.