The cable he'd use, RG-6 coaxial cable, is only as water proof as the connectors used to terminate the cable. I'm pretty sure most installers these days use water proof compression connectors, so you should be ok with that.
Do you really want a bunch of cables going from the dish in the lawn to your house just laying around? Mowing the lawn would certainly put the cables at risk, plus it would probably look awful. If this really is only going to be temporary and you REALLY don't want your lawn dug up, I suppose you could get some conduit pipe and run the coaxial cables through it with the conduit pipe above the ground. This may look nicer than just wires strewn across the lawn. It really is best to bury the lines though in my opinion.
Do you really want a bunch of cables going from the dish in the lawn to your house just laying around? Mowing the lawn would certainly put the cables at risk, plus it would probably look awful. If this really is only going to be temporary and you REALLY don't want your lawn dug up, I suppose you could get some conduit pipe and run the coaxial cables through it with the conduit pipe above the ground. This may look nicer than just wires strewn across the lawn. It really is best to bury the lines though in my opinion.