To echo Cary's comments about the community, Mr. Horiuchi has directly helped train an awful lot of FBI snipers, and that skill set has mattered to many in the law enforcement community, including via trickle down training to outside agency types. We're speaking of certification training and the like. I know him to be very well-respected among LEO sniper professionals, notwithstanding the repulsion many feel at him and what occurred. The contrariness of that pointed judgement (his/the FBI's management at RubyRidge which led to tragedy) to effective snipercraft may not always be so apparant to those so focused in training, but while many may be aware of his notoriety it falls to the wayside when getting down with the nuts-and-bolts of learning the skills. Plus many were likely just out of High School or college when the event happened and they may not have learned of it in depth.
The FBI period before the H&S Precision (and some FN) rifles came along was one rife with a mix of troubled rebarreled Rem 700's and lesser numbers of pre-64 Winchesters; these new rifles certainly provided greater versatility. This said, H&S Precision's winning the contract and the exposure so many (in the community) have with Mr. Horiuchi created a natural tie-in for a reference once Horiuchi got deeper into the program.
So with the aforementioned, my conclusion is I too believe that H&S Precision caters purely to that community and Mr. Horiuchi's reference will help sell rifles. I think maybe this is obvious, but certainly the choice by H&S Precision to use him was a conscious undertaking. It's a given it would be a lightening rod.