Oh yes, I mislooked the lines in the screenshot.
This is probably because he was not the first to order the -500 model, and there are already several other airlines ahead of him in the queue for it. And while the orders for the A330/A340 are from the same line there are still some checks on model-level (vs. fleet-level), in order to keep the line/orders in a reasonable row between all airlines. (And also since the delivery is far away still the system will leave spaces between the orders in order to keep some room for others too). But with this order rate you can expect the deliveries to move forward a bit after a few years.
From what I have observed over the past few years, I do not believe that the new type orders end up moving up. I have tried to do the same thing in several game worlds and production lines. In some cases, I will get the new type to have its first deliveries to be scheduled upon certification (yay), but the orders that I make before that end up compressing, leaving a 3-9 month gap in deliveries for me. Probably not the same exact issue, but certainly related to the following use case:
1. New model plane launches on an existing production line.
2. Airline has interest in topping off its prior generation orders before ordering the new type.
3. Airline wishes to maximize the usefulness of the volume discount by doing a multipart order - enough planes to cover the production line up to the introduction of the new model, then a clean switch to the new model when it enters service.
4. Production line compression happens.
5. Gap in deliveries happens.
6. Airline does not grow as much as it wants to grow (or perform fleet replacement).
8. No profit.