Ainsowrth was targeted because of the size of his operation. He had ads in magazines, he had a website where you could order items online, and he had a storefront with stormtroopers in the window. Oh, and he claimed to own the copyright for stormtroopers.
Lucasfilm is aware that there are hundreds of smaller armor makers (anyone ever heard of the 501st Legion?), but they get a pass because they're low-key, and bow appropriately.