I cannot see a contradiction. Emotional-objects belong more to the abstract world of ideas, which we prize. Anything else is expendable.
I agree with the previous posts. Minimalism is a philosophy. We don't hoard superfluous crap, we don't need to constantly buy buy buy useless stuff, don't need to go shopping all the time, don't suffer from the need to "decorate" and "make things pretty". If it is useful, and it gets the job done, it's fine. We seem to be able to achieve comfort and contentment with very few material possessions, because we live inside our heads more than inside our rooms. INTPs are not consumer whores, they are spartan, because they are strict in what they can consider to be necessary and useful.
And nevertheless, they hoard. Hoard books, silly drawings, old photos, random notes, napkin doodles, journals, music, etc. Anything that relates to their past, to their ideas or emotions, to the mental world. It is like their "external memory device", that allows them to keep a sort of backup so they don't forget (busy minds = forgetfulness). Ideas are a naturally obviously valuable thing to keep. Emotions, they are more like a riddle to decipher, but that provide stimulation. These things are indeed worth keeping.
Sometimes, though, useless crap does accumulate and gets left there simply because we're just too lazy to clean up, and become oblivious to the object's existence. Not because we want to keep all that crap.
Looking around, I really don't have much "possesions" : in my room, besides books and cds and drawings and models (all "ideas" or "emotions" made physical), a single 1'x1'x1' box filled with miscellaneous memory-objects, and a memento mori skull that doubles as a hat stand, the only stuff I have is entirely functional and essential to my needs: task lamp, alarm clock, laptop, camera, desk, chair, bed, drafting table. I'd easily fit most of that on a small car, sans the furniture, but that's easier to replace than to transport.
Conclusion: INTP = Minimalist life needs, idea hoarding
