Nope. With the appropriate level of suspicion, it can be detained until they are able to access it. If you use good encryption and refuse to give up the password, I guess that detention would last forever. As far as I know, that has never happened. The legal challenge would be interesting. I expect the court would consider it a seizure at that point and require probable cause to sustain it.

Laptops have been previously held to be similar to a file cabinet. I think the analogy is fair. Both are capable of holding both private thoughts and contraband. If you are crossing the border by car and have a locked file cabinet in it, CBP should certainly have the authority to open it, with or without the passenger's cooperation.