On the face of it, it looks to be a very good move. Provided the company has some good revenues, it is fine to spend some amount in weeding out the unhappy employees. The rest employees who anyway are motivated will work properly, and they will not be affected by the negative and dissatisfied employees. Just that their hiring system needs to be effective, so that a lot of would-be dissatisfied employees are not selected in the first place. Other than this, the only negative I see is that a few smart candidates may join only to quit in the coming days.