I have no idea if they would arrest every last athlete at the opening ceremony. I don't agree with the law here, but Russia has the right to make their own laws. Every athlete could not only be arrested, but also disciplined by their own Olympics committee, which makes athletes sign an agreement stating they will obey the laws of the country etc. Athletes on sponsorship deals could also lose them. If someone isn't willing to obey the law, I would rather them boycott, but I don't think a boycott would make any difference to the law. If they choose to go and break the law, then they won't get my sympathy.