I think you are confusing what I would call plan termination and plan closure.
I explain to clients that the Termination Date is the date that typically benefits stop accruing. Its not uncommon for me to see the final payroll, or safe harbor deposit go in after the termination date. Particularly the employer contributions, which may still need calculations and testing.
I use plan closure to explain that is what happens when all the balances are brought to zero. this would be after deposits are made, distributions are completed. I also find it helpful when explaining the Form 5500 requirements. Namely that it must continued to be filed until the plan balance is shown as zero.
I realize that plan closure is not a technical term and the above usage does not quite reflect the regs, but for the average client, it seems to help them make sense of it all.