fgqb#19nyj said:

It would make sense that he did retrieve it since he might have to fight his way out of the Death Star.

Thats one way to look at it. Ady might decide that its more symbolic of Luke's now very solid grasp of the force for him to throw it away and never go pick it back up.....figuring that he can use the force to just deal with anything that may come up. Additionally, the DSII is being destroyed...no-one is interested in where Luke is going at that point, they all just want off, the same as he does.