Westie its probably a good thing for you. I realize that people have been using them for a long time for steaming crabs and other uses with no noticeable effects. However kegs are manufactured with a different composition than true food grade stainless steel that is safe for high temp applications. I have been in the beer and liquor distribution business for years and I have spoken with a metalurgist (sp) from the largest keg manufacture on the east coast and he explained to me that some of the softer componets that are used in the process for durability are not safe for human consumption. Apparently they are released when the material is heated. At the time I was thinking of building a few for me and several friends but this guy told me that he wouldn't reccomend letting his enemies consume anything out of one that was used to cook in. Unless of course you are into Heavy Metal. Something to consider.
The beer distributors are probably just saying that to keep people from stealing them to make steamers out of them...my family has used them for as long as I can remember and we are only a little crazy