I don't think Gane's TDD is anywhere near proven enough to say he will be able to stop Aspinall's takedowns. He shrugged off a few lazy attempts from Spivak, but Spivak isn't a wrestler. He's a big slow, lumbering Judo guy who doesn't know what to do if he can't close the distance and grab a hold of you. Besides that, we have seen Gane get easily wrestled by Jones, no shame there.
The Francis fight is what should be worrying Gane fans. He was able to outwrestle Gane on pure strength, barely any technique. And he did so effortlessly with one knee.
Meanwhile we have seen Aspinall effortlessly takedown Volkov whenever he wanted to. A man Blaydes struggled to take down many times, a man Romanov couldn't get down to save his life.
At this point Tom's offensive wrestling is more proven than Gane's defensive wrestling is.