Gray, again, you're missing the point. If Lantz wanted to write original fiction, Lantz would be writing original fiction. He is using the Nasuverse characters because he likes the Nasuverse characters. And, the suggestion you made is one that has been made and dismissed about 5 times already, you're just flogging a dead horse. And, nor is it one which can be compromised on (either it's a Nasuverse fanfic or it's not), so there is nothing constructive about it whatsoever.
As for how you think of Lantz's work, you can treat it however you like. If you want to consider it to be original fiction which has a lot of similarities to the Nasuverse and characters with the same name, then go ahead. Just don't expect Lantz to do the same.