The Stumbler, I can understand why this is so frustrating and it leads me to believe that the WTBTS does this sort of thing intentionally. That is, they redefine common day words into meanings that don't exist and are not recognized by common use language. There are a number of words that they do this with. It is worthwhile considering why they do this.
Firstly, when they change their viewpoint on a matter they will try to defend themselves (where they can) by saying they always have had this view. Changing the meaning of a word helps them to do this so that they can say they never actually said (or meant) something that they obviously did in the past.
Secondly and probably more importantly, it allows them an easy escape route. This gives them an out for discussing the real issue at hand and sidetracks the conversation away from the very important message you are trying to get accross.
In your situation, does it really matter if he or the WTBTS do not want to acknowledge that what they believe is creationilsm? There is no point in getting tied down with one word. Just move on and get to the issues that you really want to discuss and sidetrack the use of the word 'creationilsm' because it is causing a stumbling block.
That is why I love this forum and the discussions here as they help to show the many tricks that the WTBTS has taught their followers and they have no idea.
It causes a circular thinking within the JW and they can never get down to the real issues with any logical understanding. It is no wonder that so many of them are stressed out or depressed. The WTBTS tries to rewire their brains and it causes confussion which they can't get to the bottom of, it is so much easier to accept as black and white anything that the WTBTS teaches them and this is why they will accept why 2 + 2 = 5.