Join Date: Oct 2010
Location: Brussels, Belgium
It's fine. Whether the seat post is straight or set back makes no difference for the frame, and it is more than strong enough to take that much set back, and much more. I'm actually hard-pressed to think of a situation where saddle set back would be likely to damage a frame before anything else fails.
You might worry about the saddle rails, but I wouldn't; you can see that the rails are well supported by the wide cradle on that seat post even if it does go outside of the recommended range. At your weight, you could slam it even further back on a seat post with a narrower cradle, and it would still be fine.