Um, perhaps an easier and just as effective solution might be to place a sticker somewhere prominent on the chassis either specifying the slot assignments or referring the customer to documentation.
Appropriate slots can chance depending on software version, so stickers are not appropriate.
I was under the impression there were some checks in the software, but I guess it didn't detect the patricular case discussed here. It can also be a problem if they want to make an exception for a particular customer and have to roll a special release every time for them without the check.
The biggest problem is the user didn't read the documentation. I have no sympathy for them. They get what they deserve.
Bruce