Haven't had time to do a full review, but there are actually 5 different Greek words for 'punishment' or that can be translated 'punishment' - so the article's claim that the pairing of eternal and punishment only occurs once isn't necessarily correct. (Vine's Expository Dictionary of Old & New Testament Words)

Will do a bit more digging once I have done some things that need to be done now around the house!!

Just had a further thought: Nungesser and Amirault acknowledge that the word 'kolasin' used in Matthew 25 can mean chopping off of - as in pruning a branch from a tree. This would seem to be pretty terminal, wouldn't it?  The same word is used in 1 John 4:18. 

The verb 'kolazo', from which the noun 'kolasin' comes from, is also used in Acts 4:21 and 2 Peter 2:9. 

In addition to these, Jesus teaches about the pruning of the vine in John 15 and uses the picture of the unproductive fig tree in Luke 13.

There are over a dozen English translations which do NOT contain the concept of "eternal punishment" on ANY of their pages, NOR the pagan concept of Hell.

Convenient that they don't then mention any of the dozen and more by name.  Suspicious.