Just because Blackrock was not in R116's EGPWS database presumably that doesn't necessarily mean the crew did not know about it? The notion that they were therefore unaware of it doesn't fully explain things to me. If you didn't know about Blackrock (and assumed it was open sea) would you still pick that point to do a let down? And to 220ft? It is still a long way from Blacksod, and also not in the middle of open sea to the southeast. Furthermore if one assumes that they did pick that fairly random point, why do a tear drop pattern to return right to it after the first approach? But more importantly this location doesn't look a great one to me to use for a low level straight in approach over sea to Blacksod - there are uninhabited (unlit) islands pretty much en route to cross, 3 miles from Blacksod.
So just because Blackrock wasn't in the EGPWS database could it still have been in in the FMS database? If not, could they have been aware of Blackrock from charts and entered the coordinates manually in the nav database? And presumably, given a fairly long direct track to it, the coordinates were inputted to navigate to that point, even if they thought it was open sea not Blackrock. And finally, was Blackrock shown on the moving map display that they were presumably monitoring? For example, it is on a 1:500,000 moving map I use.