Should dryer vent hose be half embedded in drywall?
While perhaps functional at present, the current arrangement does not allow for easy maintenance, which will be required after a couple years of filling with lint. It appears that it would be almost impossible to remove and replace the hose to clean it out when it clogs with lint (which WILL happen sooner or later) without cutting into the drywall.  IMO that's sufficient reason to insist your contractor re-route it.