do they lose the baseline

[JoeD1]

That's right. Check out the Nat'l Federation case book- 7.5.7B.

"Team B has scored a field goal and A1 has the ball along the end line for a throw-in. Team A is not in the bonus. Prior to the ball being thrown inbounds by A1: (d) A2 requests a time-out."

"Ruling: In (d), Team A may throw-in from anywhere out of bounds along the end line following the time-out."