I think you are looking into it far too deeply James.
The Chamber has a number of members from retail, law, insurance, engineering, telecoms, banking, IT, eGaming, travel to name a few.
All of those sectors and companies employ huge numbers of people. And those sectors support or are interlinked with everything else. It isn't about minority interests of a few. Far from it really.
As for Manx Radio joining - it looks straight forward to me. It's an opportunity for them to sell their services to a ready made audience and one bit of business covers the fee.
I don't really agree that the chamber is hugely agenda drive aside of just really wanting what is best for the island.