Do you think he could go straight from Destiny to Cold Equations, as someone that doesn't care very much about continuity as long as he can recognize most of the characters, and not be lost?
I'd say he almost certainly could. If he read and enjoyed Destiny
without having read the Titan
books or Greater Than the Sum
, etc, then reading Cold Equations
without having read Immortal Coil
or (for the second book) the Typhon Pact
stories shouldn't be an issue. Most of the focus is on characters he'll know from TV or else met in Destiny
If he knows Data and the backstory with Data's family, then everything should be more than fine. For the second book, the Typhon Pact might need explaining, but that will take about 30 seconds, I'm sure.