Courier / Trucking Business

I am looking at a trucking business that picks up freight from a major airport. I have two red flags that I am hoping someone with some industry experience can opine on:

1. Substantial customer concentration with a major freight forwarder, DSV (redacted). Seller claims this is not an issue at all as they are essentially the "Amazon" of freight forwarding and they capture a relatively minor portion of their courier business out of this particular airport.

2. They ship hazardous materials, including explosives, that help contribute to an above-average margin profile. Obviously there is inherent risk here, but would love someone else's perspective.

They have a bonded warehouse and comply with all TSA regulations. They do flatbed, LTL, FTL, hot shotting, and more. Overall this looks like an incredibly stable business with solid margins and good operations. Just ignorant of the risks presented.