Can't open the AIMs web page but what you say is interesting. A 142 school can not issue a certificate using a sim that represents an aircraft requiring a type rating without also issuing that type rating. So you could take your private checkride in a B-787 sim and have a private certificate with a B-787 type. Because a type rating checkride is always done to ATP standards, the type rating will upgrade to the commercial level if you take your commercial ride in a CE-310. And when you take your ATP ride it becomes an ATP level type because you showed you could fly a B-787 to ATP standards when you passed your private checkride. Sounds like they are trying to get around issuing the type by requiring you to already hold the type to complete the ATP ride. The SIC type wouldn't work because you have to be PIC of the aircraft (sim) during the ride and a SIC type doesn't let you do that. But it seem they have a very limited market to issue ATPs to holders of BE-1900 type ratings. Odd.