Hypothetical MH370 flight path to Perth, Australia via Cocos Keeling Island

Hover over image to open it in a larger view.

I created a picture to show a hypothetical flight path to Perth, Australia, via Cocos Keeling Island, that MH370 might have flown. This should be my last follow up to my posts here and here.

The Investigators insist MH370 could only have flown south. Their diagrams show MH370 flying close to Cocos Keeling Island and then continuing southeast after that. But with no explanation whatsoever, they use extremely slow estimated speeds for MH370, ranging from 325 kts to 350 kts.

Coincidentally, those slow speeds prevent MH370 from reaching the outer detection range of JORN until close to the time of MH370's final communications with the Inmarsat satellite.

However, MH370 and UAE343 were near each other at 18:22 UTC. Therefore MH370 would have been able to travel the same approximate distance as UAE343 had by 00:19 UTC. (UAE343 was near its destination of Dubai International Airport in the United Arab Emirates at that time.)

The only way MH370 could've gotten from its last known transponder location near IGARI/BITOD at 17:21 UTC to WMPK (Penang/Butterworth) and then to VAMPI/MEKAR by 18:22 UTC, which is the path Investigators say it flew, is if it was flying at a minimum speed of approximately 470 kts.

So why would whoever was in control of MH370 suddenly decide to start flying at a slower speed, as the Investigators claim?

And how did whoever was in control of MH370 keep the rest of the passengers and crew subdued during this more than 6 hour flight diversion?

If MH370 did fly south, which one of these stories is more plausible, knowing that the person in control of MH370 took deliberate actions to evade detection while MH370 was flying:

1) The person in control of MH370 flew south to the middle of nowhere to commit suicide, rather than doing a nose dive immediately in the location where the transponder went off.
2) The person in control of MH370 flew south to the middle of nowhere to land on the runway of a remote island.
3) The person in control of MH370 flew south to commit a 9/11 style attack on Australia, which was reachable.

Notes:
1) I am not saying MH370 did fly toward Perth for a 9/11 style attack. I am only saying that it was possible. (See my previous posts for more details on that topic.)
2) Australia has never said whether or not JORN detected MH370.
3) I used the following to plot the course shown in the picture:

Flight Path:
WMKK WMKN IGARI BITOD IGARI WMCK WMKP VAMPI
MEKAR NILAM VIROT UPROB YPCC MERIB YPPH

That flight plan and speed can be plotted on SkyVector.

Approximate times based on 470 kts:

MEKAR 18:22 UTC
NILAM 18:26 UTC
VIROT 18:38 UTC
UPROB 19:16 UTC
YPCC  20:58 UTC (Cocos-Keeling Island)
MERIB 23:55 UTC
YPPH  00:21 UTC (Perth)