Well you are certainly thinking about this from a collector point of view, and I think that is leading you to make some incorrect conclusions.
To get much information from the Extranet you have to put the old numbering system out of your head mate...if you have a mindset that leads you to thing that because it says the case is for a 280 it can't be a chronometer, you will be assuming far too much. But of course that is up to you to decide how you want to view this information.
As far as Omega is concerned 30 SC T2 is a 280, and the 30 SC T2 RG is a 281.
If I search on "30T2" under the components menu, I get "No results found" back, which is exactly what I would expect, because the 30T2 movements "don't exist" anymore.
Cheers, Al