It doesn't seem right to me either.
28-500(3)(b) also states that the switch must be a general-use switch complying with rule 14-510, I don't think the disconnect falls in to this category.
Also what about overload protection, does this installation comply with 28-308?
Wasn't exactly sure what you meant by this,
did you mean there are three fuses that are all different sizes? That would really not be good!!