They would be re-tested to the point that they still get the 5GHz clock as 8-Pack stated but the temp is still not relevant for their sales point in that they do not state anything about it.
And yeah it may seem that it is a politician answer but it is exactly what is being sold and thus deciding that just because you want it to be lower temp wise doesn't make it so :/
What is being sold is a binned CPU, capable of 5Ghz, and has been de-lidded in order to replace Intel's TIM with liquid metal. If the de-lid process is done properly (and anyone buying one of these CPUs would reasonably expect the job to have been done properly), then the expected load temperature with a good quality cooler would unlikely to be over 80C. OK there's no guarantee of what temperature each CPU might run at, but it appears that one customer achieved ~20C reduction by "tidying up" the de-lid process that had already been carried out. If the customer thought "that temperature seems a bit high, might be a dodgy de-lid", then a simple test would have shown the same issue before the CPU was sold.
I assume that there's added cost in carrying out the de-lid operation, so it's reasonable to expect that the process will be carried out correctly in order for the CPU to run at a significantly lower temperature than if it hadn't been de-lidded.