Google is obviously wrong :) This line can be "declined" if Black makes an answer to 4.b4, and that answer is not "4...Bxb4".
I found another reference here:
I think whilst what you said sounds sensible, maybe the "declined" in this case means outside of the normal Evans gambit with Ba5. It seems that all the Ba5 variations are in C52. Perhaps that is considered the standard "Evans Gambit".