If you're a modular home builder, why wouldn't you reveal your manufacturer?

After 15 years at this gig, I've had my fair share of odd and unexpected interviews. From having a gas line ruptured by someone installing posts in the parking lot of a modular factory as I was interviewing the president (the image of my photographer at the time, leaving me in the dust as he ran full tilt toward the exit during the mass evacutation, will remain one of my fondest memories) to having the police arrest the bookkeeper at the office of a builder I was interviewing (for meth production in a motel room, of all things), or having the owner of a log home company brow beat me for a solid 30 minutes about a story I wrote on his company in a previous issue--he objected to the phrase, "cash infusion" in a story. (His argument being he didn't need any cash infusion, a matter of pride, I suppose.) But why do you suppose a modular home builder that I am writing about not reveal the manufacturer they were using? Any thoughts?