I'm not condoning what ATC did or how they responded, but like the UK pilot
that continued on single-engine across the pond I wonder why AA continued on
past a suitable airport once they knew they had a problem. That's all I'm
questioning.

In fact, it was a British Airways 747 that continued on three engines, not
one. Here's an interesting column about that the incident:

http://www.avweb.com/news/pelican/193882-1.html