Never mind. The solution is Edit->"Edit as text". Don't know why the IDE thought that the log was a binary file.
Well, the detection is quite simple: If it contains chars <32 other than \t \n \r, it is considered binary.
Anyway, I am running to the same issues with .log from time to time (it is quite easy for some <32 chars to 'escape' into the .log), so I agree that this still needs some tuning.... Perhaps further detection based on extension would help here or something like that.