I wondered why the deauth in step 1 works, it sure looks like that's one of the shortcomings in WPA and there is just no workaround - except going with WPA2.
http://security.stackexchange.com/questions/20219/preventing...
http://security.stackexchange.com/questions/20219/preventing...
802.11w aims to address this by authenticating management frames but is slow in coming to market and plagued with interop issues: http://en.wikipedia.org/wiki/IEEE_802.11w-2009