The details are that the reporter asked him why he was vetting and allowing only people who are from the 1st district into the town hall, and shouldn't all Iowans have a right to be in attendance. He responded "No, I do not represent all Iowans, just the ones from the 1st district". Now, strictly speaking he is correct on that point.
The follow up was of course perfection with the interviewer asking "Would you accept a campaign donation from a republican outside your district?" to which Blum stormed off. THAT was a perfectly appropriate question because you know that he most like HAS gotten donations from those outside district 1.
Clearly he's a weasel. And he's less than pleased that he just got snake bit.