Tierney struggled with injuries up until the lockdown after moving from Celtic last summer.
In a post dedicated to Morgan on Twitter, Tierney wrote: "This man helped me from the first minute I walked in the door! Cannot thank you enough for everything you've done for me. A special man. Grateful for everything.
"So sad to see you go gonna miss you so much legend. Thank you. Couldn't have done this without you. Love @ChrisMorgan10 hero."