Flynn, think of it another way. It's like walking into a branch of Curry's and asking them if you can buy a B&O Hi-fi. Yes they would love to sell you one but they don't have the accounts, contacts or NEED to sell them.
That's how insurance brokers work, the brokers sell packages of insurance from insurers. Greenlight for example struggle to insure BMW's due to historical claims, A-plan declined my postcode a few years back. However all use the same insurance companies somewhere along the line it just depends on what product, agreement and contracts they have in place.
I, and Chris at Sky will no doubt confirm, if they COULD insure you, they would, but they simple don't have the product to do so.
Does that make sense?
Mike