"Is there any shred of truth to this statement?"
"so they’re far more inclined to fly at a slower pace"
Flying slowly for more coin, yep, seen that in nearly every airline I have worked for, contract pilots and full timers alike.
"hire in subcontractors to fly their planes, meaning that they have a fraction of the experience of a long-term employed pilot and are likely to have only a fraction of the training."
Actually, in many cases the reverse is true. Korean/Singapore/Vietnam etc.