Thanks for the link...
Interesting reading, however I do not think after reading this blog that I would come to the conclusion that there is an ongoing issue with catastrophic failure.
I read that one guy and one gun had this problem and that the blog author himself speculates that the problem was likely caused by hand loaded ammo (which also may be the reason that FN is declining on warranty).
I have never ever heard of this happening on any other FN57 and the design of the gun is probably the most reliable that I have ever seen in a pistol (no feed ramp and the mag feeds the round into the chamber with a straight-in motion which eliminates any chance of stovepiped rounds).
I would not hesitate to continue letting my 12 & 15 year old operate this firearm.