I don't think that's accurate: Carlsen could have gotten a winning advantage just by defending everything with Qg3. On chess24's broadcast, Svidler even thought Carlsen might not go for the mate just because Qg3 was safely good enough.
The trick is that he was under time pressure and if he miscalculated faced a mate in one, so it was somewhat risky (and why Svidler was surprised he played it).