Sorry to hear of your problem. The bolt size did change, at least on the 91-96 cars. I use alot of Global West bushings, and the inner sleeve is offered in 2 sizes for different applications. Pre-91 cars were 9/16", I think.
Looking at the GM parts list, all 91-96 cars use a 14mm bolt on the lower control arm pivots--there is nothing special on the 9C1's.
If others have used an Energy Suspension kit with no problems, I'd have to assume that there was a packaging problem, and you somehow ended up with bushings that had the wrong inner sleeve installed. I'd persist with Energy to make this right if I was in your situation. It is alot easier for me to say that with Energy just "down the road" compared to your location on the other side of the country--but I've never dealt with them, but I do know they aren't interested in having anyone into their facility, and I've only ever been able to get answers to my questions through retailers, so you got further than I ever did. If I could find my ES catalog, I'd look to see if there is any listing difference by year, though that alone would not show the sleeve diameter difference, unless it was in a footnote.
Good luck, let us know how things turn out!