Pace doesn't come from strength.
Strength and conditioning work isn't just about upping your bench press PR 😅 are you trying to suggest that fast bowlers don't have extremely good lower body and core strength to enable them to consistently bowl fast?
No, being strong isn't going to make you a quick bowler, but there is clearly a relationship between consistently bowling quick and having a good level of S&C.
I'm sure Robinson could bowl a pretty quick ball, but it's about doing it consistently and accurately over the course of a match. I imagine that's why he'd be on an S&C program from the England management.