It doesn't say that you have to keep all the same materials, just that you have to use a bushing that uses the same material as original. Does that rule mean that you can replace the plastic/rubber/plastic sandwich that makes up our bushings with a straight plastic part of the same material?
Don't torture the rule. Just put OE back in. I would protest you if you had aftermarket bushings that didn't match the materials and dimensions of standard... and I don't protest.