Thank you for providing the tweet, I don't have a twitter account so finding things like that is quite difficult for me.Here is the aforementioned tweet. And yes, Silent Storm's opening chapter certainly shows off a degree of their physical strength. To restate the conditions, Blue Team holds fast against 30 Gs of acceleration in the slingshot manoeuvre by physically grabbing their teammate's thruster-packs for guidance. The column they were chained in was "undulating", meaning that it was waving side-to-side. The Spartan at the back would be experiencing the most torque relative to their bodyweight, in that case - making for a decent counterbalance to what the second to first is experiencing via sheer weight.
Coupled with his 130 kilo frame, John would weigh close to 578 kilograms in his COBALT armor - given how the suit itself weighs 56 kilograms on Seoba's ~0.125G gravity. With that in mind and peppering down the average to 567 for the 4 of them, the Spartan second to John would be holding approximately over 51 tonnes of force with subtle changes of torque -This is a similar number I have derived by their Monolith push in The Fall of Reach. While these numbers may seem outlandish, they do give some weight behind their other striking feats where they punch through MBTs, Pelicans, and even the haulage deck of the Forward Unto Dawn in Halo 3 (Which was notably unscathed by an M12 and later a M808 crashing into it).
To remain on-topic, this would imply unarmoured John as being a ten-tonner in certain translations (as much as I try to avoid the force-multiplier purview, if other franchises are any indicator of how much of an extraction and reliability fiasco that can become).
I just want to point out that his answer seems to be specifically directed toward Lucy and Tom aka Spartan 3s. The reason I find this of note is due to various media pieces implying that Spartan 3s are not on the same level as Spartan 2s. It could be that in Denning's mind Spartan 2s are fairly superior to Spartan 3s. I was always disappointed by the depiction of Mark vs Ota Gallo in A Necessary Truth considering how superior a Spartan 3 should be in relation to a normal human. But I guess this is the result of the plot often needing regular humans to sometimes match or even beat Spartan level individuals.
From which novel is this 20 km/h figure? I don't recall reading that recently so it may be from a book I have yet to buy.
Is John a 10 tonner whilst in armour? Also have you taken into account the differing levels of enhancement that each Mark provides (such as x2 for mark4 and 5, and x5 for mark6)?
Then again I'm not even sure authors actually care about this particular notion since there doesn't seem to be much of a difference between the depictions of Spartan strength in mark 4 and mark 6+. This could be due to the fact that in some of the recent adaptations of the Fall of Reach (comic/animation) they changed the value from x2 to x5.