That warrants nothing in regards of functionality. It may no be ilegal to try to run SOME parts of the code (some parts aren't legally part to the GPL license), but that doesn't mean at all that any theme should/must successfully run on any wordpress environment.
Just strip out the CSS & JS code that doesn’t directly interact with the WP api’s and your done.
I would love to discuss WP, its derivatives (themes and plugins) and licensing, but there are already a ton of discussion made about this, both on and off BHW.
Having said that, in my opinion the Envato hybrid/dual license model remains an akward one.
Personally, I could care less if someone repurposed my CSS/JS/PHP for fun and profit. After all I’m standing on the shoulders of giants. People who figured a lot of this stuff out and where willing to share their knowledge for free before I came on the scene. Sort of like this forum, but I digress.
The only weight behind the Envato dual license is money. If that makes them happy, I’m fine with that, and to each it’s own I guess.
But let’s not fool ourselves or each other. With a few exceptions a lot of the Envato themes are bloated bs that are great at one thing, and one thing only: setting false expectations.
When you move out of the Godaddy/Envato phase, and actually start to understand WP and the difference between reliable hosting, people tend to completely forget about Theme Forrest.
You should always ask yourself the question what problem does this (technology) solve. The second one is to ask who is actually benefiting from this. In Envato’s case it’s not the customer