That was the first thing that caught my eye when Poboy question the authenticity of the photo... but then again... he is running the engine with an open exhaust port - no muffler, nor exhaust pipe. Seems right up FreeRunner's mentality!
My understanding is it could lead to a burnt/warp valve, or lean out the running mixtures, not sure if those are a real issues on small engines, just what I've read what not to do (& I'm not dumb enough to try it)... I'd be more concern about debris from this "Trench Digger" entering the port and fouling up the valve/piston.

This thread is like a train wreck in slow motion. Chugga-chugga-whoo-whoo!! Train isa coming...