Of course it's better to have distributions after the end of the year for this situation as K2retire said, but if the document does have immediate cash outs for a balance forward plan, I don't see why the amount of the distribution can't be the vested amount of the latest valuation, plus any current period deferrals and Safe Harbor contributions. No current period gains or losses.
It requires a little extra work to find out from the employer the compensation to calculate the Safe Harbor, and to find out the deferral amount, but it's not that hard. And with a balance forward plan, it doesn't even matter if the employer has deposited the Safe Harbor yet.
Of course one has to look to the document, but I think most are silent on this issue.
I would be interested to hear if others think this is not allowed, as depending on the situation, we have done this.
Of course profit sharing is a different story, and depends on the plan design. Most of ours have 1,000 hours - last day for PS, so unless there is a testing problem, the terminated participant is not getting that piece. If they do get a PS, then that part would require a 2nd distribution (unless it is a fixed required pro rata ps).