EgyptAir 804 vs MH370

Someone suggested that the EgyptAir's maneouevers just prior to the crash was similar to MH370's nearly-180deg course deviation so I spent some time reading up on MH370.  In short, they appear to be very different scenarios (with the info we have at this time).  Whereas MH370 most likely started off as a highjacking, EgyptAir 804 is more clearly a sudden loss of control of the plane.

The data points to MH370 being a hijacking - the strange co-pilot choice of words, the transponder turned off manually, plane taken to a hypoxia-inducing 45,000ft , possibly to knock out passengers to avoid either a passenger revolt, or cell phone usage . However, the highjacking either failed to complete, or there was a failed attempt to take back the plane and land.  There is no evidence of lack of control or mechanical failure for the many minutes between loss of ATC contact, and the last primary radar sighting over Malaysia.  The move to 45,000 feet was deliberate. And to be fair, to this day, no theory perfectly explains all the data, leaving all kinds of room for conspiracy theories (Pilot blackmailing for the release of a political prisoner, necessitating flying around during negotiation, etc). But more likely the reason is a compound one. Here's the best summary I've seen of the possible MH370 scenarios, but these graphics also spell out the facts:

The EgyptAir plane, on the other hand, never lost comms and reported massive successive system failures -  unlike MH370 - that led to total loss of control of the plane.  The final ACAR messages were supposedly these:

00:26Z 3044 ANTI ICE R WINDOW
00:26Z 561200 R SLIDING WINDOW SENSOR
00:26Z 2600 SMOKE LAVATORY SMOKE
00:27Z 2600 AVIONICS SMOKE
00:28Z 561100 R FIXED WINDOW SENSOR
00:29Z 2200 AUTO FLT FCU 2 FAULT
00:29Z 2700 F/CTL SEC 3 FAULT

"Former National Transportation Safety Board investigator Greg Feith said the fact that the smoke warning occurred so soon before the plane disappeared suggest something more catastrophic than a discarded cigarette or electrical fire."

Considering the final two messages, "First, there was a problem with the autoflight control computer. the jet would have been flying near its maximum speed and elevation at that time. That is the most efficient way for jetliners to fly, but pilots prefer to rely on autopilot systems in those conditions because if they were ever to lose control of the plane, it could be hard to regain...pilots call those conditions the "coffin corner."  Then the spoiler elevator controller (SEC 3) that controls the flaps responsible for pitch and roll control, failed as well. "It looks to me like you have a progressive flight control system failure," Mr. Mann said. "

But what is very interesting, and unexplained, is why both of these planes deviated off course at the FIR boundary, the handoff between ATCs.  Coincidence?
Here is MH370:

And also unsettling is the possibility that 804 was carried out by a terrorist who simply failed to or did not see a reason to publicize their motivations - much like the San Bernardino attackers who made no visible public claim of responsibility.