In Chapter 15 of To Kill a Mockingbird, why did Heck Tate and the men accompanying him want Tom Robinson moved out of the local Maycomb jail ?

Sheriff Heck Tate must have had an inkling of impending
trouble from the Old Sarum crowd concerning the incarceration of Tom Robinson, and he
came to discuss the matter with Atticus. Apparently, Tom was set to be moved "to the
county jail tomorrow" (it was Saturday), but for whatever reason, Tom was instead moved
to the Maycomb jail. The entire town must have known about this, and later that day,
Sheriff Tate was called "off on a snipe hunt"--a false call that sent him "so deep in
the woods they won't get out till morning." Whether Sheriff Tate notified Atticus about
this is uncertain, but Atticus decided to go to the jail in order to protect his client.
Sheriff Tate's "uneasy" feeling proved true, because a lynch mob from Old Sarum soon
showed up while the sheriff was away, leaving Atticus to deal with the group of would-be
murderers alone.