That deletes ALL of their bricks, whether they built something good or not. Doesn't sound very nice.
A while ago I made a script that checked the number of bricks that player had, and if they had less than a configurable amount of bricks, it would delete them after a configurable amount of time, and canceled the deletion if they came back.
I don't remember if it worked, I don't remember where it is, but I'll see what I can do about remaking it.