Fair that he hasn't shown a lot defensively so far, but he's also only played in Toronto and Detroit so far, neither of which play particularly effective defensive systems, so it's hard to say how relevant that is to how his defensive game under Trotz will look. With Lou likely being familiar with him as a Marlie while he was GM in Toronto, I have to feel he wouldn't be bothering here if he didn't think Timashov could execute Trotz' system, and that's what is really important -- for example, Martin was never very good defensively either, but he can execute the Trotz' system so has been good defensively within it.
But I do agree that his ability to play a defensive game will be the biggest factor as to whether he can hold down a spot in the bottom 6 or not. I just don't tend to think of defensive acumen when I think of what a player is built for and was a little confused by the phrasing, so thanks for clarifying for me.