If you scroll up and choose "Linux swap" the Mount Point option is disabled and changes to "Swap Partition", however, if you press the up key again the Type box will stay on "Linux swap", but the Mount Point box will be re-enabled (pressing up again makes it disable again... repeat steps 1- 3 :) ). What Disk Druid does when you press "Ok" then changes depending on whether or not you filled in a Mount Point. If you did, it decides you must have wanted a "Linux native", and if you don't, it build a "Linux swap".
verified ... thanks for your report!
Fixed in internal tree - needs verification.
verified fix in internal build