I think he says ISIL becuase the low information voter will think ISIS is Bush’s Fault and ISIL is short for icicle pop - they taste good.
ISIL is short for icicle pop - they taste good.
Interesting article about the meaning of ISIL
http://beforeitsnews.com/global-unrest/2014/09/the-coded-message-obama-delivers-when-he-says-isil-instead-of-isis-2460550.html