The ground is higher there too, albeit not quite as high as to the north.
The major problem in that sector to the west is that the VFR routes require you to be above a certain height because the 2 inlets you fly over (check google - line straight from the North side of IST to the crash site) are also bird sanctuaries.
So..... if ATC are pushing you up to run in the scud at the cloud base to avoid the birds, inadvertent IMC comes into play. Likewise if it's bird migration season (no idea my end of if is or not), then potentially a large flock from the sanctuary might have an effect, either by bird strike or by contributing factor in some way.
Not nice any which way. RIP.