I think that being pretentious goes hand in hand with being pedantic. Acting like you have every nuance and detail figured out. And that's very Ti.
I've seen ESFJ's be pretentious jackasses, saying that what they believe is superior because it's what they and their families have believed forever and ever (which is Si justifying Fe by using Ti as a discerning mechanism.)
I've seen INTP's use it as a tool to push people away and then believe that they somehow are more objective for doing this. By pushing people away, using just Ti, they prevent people and their emotions from encroaching on their 'amazing' rationale. And they sit there and smirk from there perch. Only later do they realize that they're jackasses and that that's not what they really wanted and they hate themselves, quite secretly, for it.
Even if pretentiousness does pertain to intelligence it does intelligence a disservice. The ultimate goal of Ti is to gather as much information as possible to make an informed decision. Being pretentious is socially objectionable and thus a road-block to open dialogue between individuals, a hindrance to the collective sharing of ideas.