I'll show you possible ways E-Thug could of created those models. Models can be copied, modified, ripped, or custom created. Here, I'll show you possibilities on how they were not made by him.
Original models can be taken and modified into a new model, like E-Thug had done in his comic where he had traced and re-drawn images that isn't technically custom made.
Here is one of his pictures to his model:
And here is a different model that I have found. (Link here)
They may not look the same, but they have key similarities. Here is a photo of them morphed together.
Look closely at each of these spots.
Although there are a couple of differences in these models, there are still similarities that goes with them. The one on the right is most likely to be updated and tweaked, just like the traced comics of his.
Picture Reference+Custom Content:
Pictures can be used as a reference in creating models. E-Thug could use a couple of his characters in his traced comic and place them as a reference in the model to copy from. Here is an example of a picture reference used in creating a model.
Content can be ripped directly from a game and then modified to fix any errors. When ripped content is put into a program, like 3Ds Max, they can contain many errors, missing textures, and missing model pieces. They can be ripped using a 3D ripping program to rip the bipeds out of the game and convert it into a 3Ds Max file or any other format. They can be modified and fixed up easily, but wouldn't be the same as the original model. The possible games that could of been ripped for this and other sonic models E-Thug has introduced would be: Sonic Unleashed, Sonic The Hedgehog (Xbox 360, PS3), Sonic And The Magic Rings, and/or Sonic And The Dark Knight. In his description of his model, he mentions about some errors that needs to be fixed.
Here is part of the description in his website about his models.
Generally, there are many possiblities on quote: "How I stole this one", however, there isn't an answer yet of which one of these techniques he has used. He could of used a combination of these in order to crate each of these models. One thing is for sure that he is a notorious liar that has and always had been tracing other people's content into his comic. It's most likely that he has used both the Picture Reference+Custom Content method and the Copied Model+Modifying Method.