Nah i don't think she is not ticklish at all i don't think there is a person that is not ticklish at all on any part at least  most people aren't exp girls/womens    it depends how much or less you are , also Araragi seems to be kinda a bad tickler lol he didn't tickle much of her sole , i bet if you were to be more violent to her foot/feet she might give a smile or a giggle at the very least also she might be rely ticklish on other parts of her body how knows , she is not  *that* ticklish like most girls  that for sure i was a little disappointed on that scene as well but she still  look to be sensitive either way. 
Also what happen  to TT ?  it is down for a wile now , i gives me ''database error'' , dose anyone have the same problem ?