Foul pop in lbt but player in dbt
 

I had a play yesterday where a foul pop up was hit by the third base bench. There was a white line marking DBT by the bench. The third baseman slid feet first and ended up with half of his body in DBT. The pop up fell to the ground in LBT. My question is if the third baseman had caught the ball while halfway in DBT would it have been a legal catch?

Under what rules:?

FED: DBT lines are in play; can make catch while touching LBT with any part of body

NCAA: DBT lines are in play; must make catch before touching DBT with any part of body
OBR: DBT lines are out of play; must make catch before touching DBT with any part of body (except dugout)