Since he is already home, isn't it right to use a past tense and say "I got sent home"?
The speaker has used "get" as it is important to keep tenses consistent. He uses "sees" earlier in the sentence, so "get" is most appropriate here. If he had used the past tense instead from the beginning, then "got" would have been more appropriate: "Principal saw Bryce on the floor, I got sent home." Ex: The dog pooped on the carpet, I got angry. Ex: The principal saw me skipping school and sent me home.