I wouldn't exclude it, it worked well. Let's not forget that they eventually still unlocked the phone with a similar tool anyway. It's only possible that these tools weren't as readily available on 2015.
I was only following the mainstream news headlines back then... not paying super close attention... but I failed to read that part. I assumed they were never able to access it to this very day.
Along with 99% of the rest of North America who can only read so much about computer security I am sure.
> On March 28, the government announced that the FBI had unlocked the iPhone and withdrew its request.
> The unidentified method used to unlock Farook's phone - costing more than $1 million to obtain - quit working once Apple updated their operating system.