As I clearly stated, Reddick was already signed to a three-year contract with the Eagles in 2022, so the Steelers signing Reddick this year instead of extending Highsmith was never even in the realm of possibility. So, kindly, you have no idea what the hell you're talking about.
And, no, the Steelers don't "always sign their own guy" if it's close, because you may recall that they let Bush and Spillane walk while also getting rid of Jack, and replaced them with a couple of inside linebackers who most of us had never heard of before.