Hi ToweringCU. (see my thread about TCX as well, it doesn't seem to be going too well at the moment for them!).
The main reason for the tech stop could have been the prevailing winds. If they had a slight tailwind going to Sharm, it might have just been enough to get them to SSH whereas with a small headwind the other way, it probably just tipped over the max range. Also, the journey to Sharm may have been with a lower payload (hence ability to carry more fuel if the flight was restricted for TO). Was your flight full by any chance?
I'm not sure about the TCX 757 fleet, but chances are that this so-called 'light ac' probably had the fuel capacity to make it comfortably. After all, 757's regularly fly transatantic. However, a common practice among airlines is to artificially limit the MTOW of the aircraft therefore putting them in a lower band for air traffic charges and landing fees. The aircraft is therefore not legally allowed to operate above this limit even though structurally it can. It would have to be recertified. Some aircraft are ordered without a centre fuel tank so it may have actually been fuel limited. One of those two possibilities anyway. What is the runway length at Sharm? That could have been a factor although unlikely. As you can see, there are many possibilities.
Your aircraft was probably therefore a substitution as another 757 had probably gone tech earlier in the day and this was the only option available. Better to get there with a delay than not at all...no?
As for the landings, well I can't comment. Sometimes you do greasers and other times you set of all the seismometres in the vicinity. Might have just been bad luck or perhaps there was some windshear.
Maybe someone with insider knowledge would be able to give you a more detailed explanation.
Regards,
Champ