That is a dowel hole, not a bolt hole. Note that it is much lower and does not have a flat surface for the bolt to seat on. Note also that it is very close to a bolt. The hole is intended to have just a thin "flash" of metal closing it off for appearance purposes.
I agree with bigted that Honda, as a premium brand, should have done better - but those side valve engines are their cheap line of products. Frankly, I would not consider it to be equivalent to a GX120 - I hope it was a whole lot cheaper, and even then I would not have bought it for a mower. They may have a mission doing jobs where they will be permanently dirty and neglected, in a farm shed in the most remote paddock, and only fired up occasionally, but to me, that is about it.
