Yes we disagree but your option observations are not entirely accurate. The two strike OTM strike call for VIX has a delta of .18 in MAY.
Delta is a theoretical value and the MM is not bound to move the option by the delta. For example, GOOG was down $0.71 to day to $408.95 and the MAY $410 PUT with a delta of .49 was down $0.20 based on last sale. Time Value premiums take in some of the expected move and therefore the option does not move its exact delta. Also as a theoratical value, it is off based on all the incorrect assumptions of B-S model (constant vols, etc..)
Second the VIX was down .24 today and the MAY 12.50 strike Call was down $0.10 even though it has a delta of .59. You will rarely find an option that moves its exact delta because delta is not constant, even if it were not theoretical. So VIX is not behaving any differently than any other option chain I have seen.
Finally you are comparing the delta of today to the 1.00 move in VIX over a few days. Delta does not work that way really. YOu cannot take delta for a move that occurs over 3 or 4 days since even in theory delta/gamma are constantly changing.
Your observations are normal moves for options and not indicative of anything out of the ordinary. Compare the VIX options to GOOG or IBM and you will see the same movements.

I do not think you can prove or disprove this based on small fluctuations in the price of the underlying or VIX. Smae way a GOOG call or put is not going to change significantly from small fluctuations in price like today. Also, MM price options wit time value premium and vols in mind which also affect changes in the options prices. If expectation is low that an option will be ITM than small moves will not budge the option price, even with a delta of .20.
The only true test is a 30 point spike in VIX honestly. For now, I have been speaking with as many traders as I can who seem to think that the options would have to trade close to intrinsic.
Quote from rallymode:
You are incorrect on that one, usually 2 strikes OTM have a delta of about .33 so each point would move the options .33 cents. But VIX isnt normal in any way, thats the whole point i am trying to get across so comparing it with normal option pricing isnt realistic.
But we already agreed to disagree on this one, didnt we?