All sony models (I've ever encounter) do that!
I believe that this is in fact a real design feature (not the "unwanted kind" reffered to in sarcasm as a "feature"

).
I'd expect (like most people) to have the scart switch over to the av channel once the machines switches on. Maybe I've just become accustomed to my vcr and satellite doing these things...
The other great design thing is if you switch on the machine from the power off position, it quickly powers on and then goes to standby. Try it without a disc in the machine. All you have to do is power of the machine on the front panel (physically and not by remote) and then power it on, you'll see what i mean .

....Then to put a disc in you have to press the power button on the remote of any key on the front panel (eject) to get the darn thing into life.....bizzare...