I find Mr. three stripes to be marginally persuasive at best. The thing she said, which I believed the most was: "I don't know". I'd go with that for a lot of what he said.
There is no published airspeed for an inflight restart of a stopped Cessna engine. It's actually pretty hard to get mechanically sound Cessna 152 engine to stop turning in flight. So, if the engine actually stops completely, I would be suspecting a mechanical failure inside. Sure, at any airspeed you like, try the electric starter, if it's going to run, that's a really good first step. If the starter won't turn it over, I'd be setting up for a forced approach. Though Cessna POH's do specify an airspeed following engine failure, that's for optimum glide, 60 knots is not going to windmill start a stopped Lycoming engine with decent compression. They do say that if the engine has stopped, to use the starter.
Turbine engines are different, and do have start envelopes, which may include a specified airspeed.