A single claim of success is not a proof of success. The starter of that thread never answered any questions about his results. He did not provide any analytical or otherwise credible evidence of his methods. Nobody replicated the results successfully (you
wrote in that thread that you would test this, did you ever try?)
As it stands, the method is not proven at all.
If dry ice is a problem, then there is another method you could try:
Another way of partitioning 1° and 2° amines from 3° amines