One of the things that I would be concerned about is not really a plan issue. How are the faithful employees who remain going to feel about having to wait until year end to receive their contributions when they see terminating employees receiving their contributions right away? Could be a can of worms the employer is opening here. I could see people wanting to "terminate" just to get the contribution then get rehired. I could see long term employees being upset and productivity going down. I think there are bigger issues here than making life easier for distributions. What you are doing is rewarding people who terminate and in business 101 you learn that you always get what you reward.
A better solution, since the plan has no last day rule and the employer is inclined to be generous to terminating employees, is to eliminate the 1,000 hours rule and just start making contributions payroll by payroll. This accomplishes the employer's wish to simplify distributions but doesn't overly benefit terminating employees compared to those who stay.
From a plan standpoint, though, I think it could be done as you describe.