If that were the case, GPS users throughout the region would have reported erroneous behavior of the units, by now.
Okay, okay..., it’s just the Bermuda Triangle of the Indian Ocean... :-)
Not necessarily. As the pirates most certainly use non-military GPS, it can be jammed or even spoofed without disturbing the rest of the region’s traffic too much, as far as I know, and I bet Navy ships are somewhat equipped with Electronic Warfare devices. If the ships in place there were spoofing the signal, they could have navigated the pirate ship anywhere, really.