He (Seymour) seemed to me like an INFP enneagram 9w1. He wasn't a T, so we can rule ENTP, ENTJ, INTP, INTJ, ESTP, ISTP, ESTJ, and ISTJ. He had no Se, so he definitely wasn't an ISFP or ESFP. He wasn't an extravert, so he wasn't ESFJ, ENFJ, or ENFP.
That leaves either ISFJ, INFJ, or INFP.
And since he had very little evident Fe, that leaves INFP.