I had a feeling this came up somewhere, but couldn't recall where, thanks...
That being said... not cool!
I'll try to include a houserule in which one could perform a faster action as a slower one. A standard as a full-round, a swift as move (or standard), etc.
Otherwise, this can hamper or negate the use of some valid resources by the players... That doesn't seem fair to me.
Example: a wizard that prepared a quickened "Dimension Door" spell to escape battle and happened to perform an immediate action, would be denied the use of that spell, even if he opted for casting it as a normal one (losing the slot he prepared the spell on, even if higher due to the metamagic modification).