I think the default is off, but you can check using the iw utility.
It might be. The default is 0, which means "no restriction, try to connect even on a bad link"
Current snapshot works on other platforms so it is probably just the drivers used on this one. Like I said, this is the nature of snapshots - the developers working on this device will get round to 802.11s support in due course I am sure, given that you have reported it.