he should have written a bit more clearly for those like me
Absolutely!
It's as clear as a CASA exam question... where the technically correct answer is most appropriate, though you have to read eight separate sections of the Regs to arrive at that answer.
Flaming it for the Level 4 English is just flaming for the sake of flaming though. Not that there's anything wrong with that - spelling and grammar are the only way you have of showing your intellect on the Internet, and as pilots we tend to expect high standards of ourselves as well as others.
Back to the topic though, his point appears to be is all this system intergration leaving us open to rare failure modes that take out all critical systems because the all suffer from the same design flaw? If so, isn't the cheap and effective solution a portable GPS capable of providing reasonably accurate navigation information far superior to a clock and compass.
The chances of you having a common fault on the same piece of equipment at the same time is relatively high compared to having the same fault on two completely separate and independant systems....
Operating 4 engines in N+1 or even N+2 / 2N isn't actually that great if they all share a common fuel source. That's why we have multiple tanks and demand the refuellers test for water, etc.
As we've seen with this incident, operating 4 GCUs isn't much to write home about if they all share the same environment, and hence subject to environmental issues like water under the floor, fire, etc.
Operating a 747 with 3x IRS, multiple screens, standby signal generators... and a Garmin 296, well the Garmin isn't going to save you from a loss of RAIM due to lack of visible satellites that's the job of the VOR, DME, INS... but it may just save you from a loss of electrics.