“why not use tracks from S2Blue as well?”
Well, unless we ever find out WHO the individual actually was behind the idea on the programme at the TV company (indie producer?), and whether they are a jingle fan with actual knowledge of JAM and PAMS stuff and “knew” what they wanted either roughly or quite specifically by cuts, or “just asked a mate who knew about these thingyies”, or whether they just gave S2B a budget and a list of “lyrics” and “left it to Simon & Co to do the honours” then….?
I’m sure though that a lot of viewers in the programme’s “target audience range” (especially e.g. Beacon Radio area, West Central Scotland, and quite a few more) would have had their ears prick up when they heard most of the items 
If it had been Alfa tracks…well, if pre-JAM UK representation era i.e. Alan F – maybe “too old” for the audience; if 1990s Alfa custom then maybe not so recognisable as fewer stations using them than the JAM-based stuff? But the “most-familiar” (and most “still stuck in their heads” being late 1980s/early 1990s JAM – which, after all, is EXACTLY what they were designed for in the first place!)