I don't blame them for not wanting to sell to homebrewers, I wouldn't. Think about some of the threads on this forum detailing the massively dangerous and dumb things people do with kegs, and then think of the liability. Many many homebrewers love to crank the pressure up on their kegs for burst carbing, and do other things that create much higher pressures than the kegs would see in a commercial setting. For commercial use the beer is already cold and carbonated before it goes into the kegs, and the highest pressure they see is when they get purged during the cleaning process. The burst discs aren't foolproof, and even if they were, a keg pressurized to 90 psi is a dangerous situation, period. I agree that the average homebrewer could utilize these kegs just as safely as (or even safer than) a commercial brewery, but that's not who they're worried about.
As for acquiring these kegs, it's easy enough if you make friends with a local microbrewery. If you do this, please be aware that they're more dangerous to work with than SS kegs, and handle them accordingly.