I'd suggest that it was entirely dependent on ownership of the relevant land, and what covenants and rights of way there are over the gateway. It could be, for example, that there is an access agreement via the platform were the main drive to the Golf Club to be blocked, for example, or likewise if there was an emergency egress route needed were the footbridge to not be available.
I can't really see how Network rail could oblige a private landowner (assuming that's what the golf course is) to allow people to walk over their property, any more than the Golf Club could oblige Network rail to allow people to walk randomly over railway property. Similarly, there would have to be good reason for unilaterally blocking the gateway unless any agreements were cancelled (or there aren't any) - on both sides.
Before any specific answer could be given, you'd have to know who owns the land on both sides and what, if any, agreements were already in place. By the time Network rail had faffed about with that, they may as well put a lift in the footbridge - and for a category E station, I can't see that happening any time soon...
Curiously, the station is given an accessibility rating of B2, which is "Some step free access to all platforms - please check details.", but then it goes on to say Platform 1 is only accessible via footbridge. Was the Gold Club the previous access point to that platform?