The orange cable is RG6 direct bury. It’s orange so if your digging a hole, you can easily identify the wire.
I believe RG59 is acceptable between the Hopper and Joeys.
However let me say this. Unless the wire is inside the walls and is inaccessible, it should really be replaced. How long would it take for the installer to pull out the old wire and run all brand new?
What people fail to realize is that the installer is being paid to run all new wire for your install.
It might be cool at the time to say it’s Ok To use the existing wire, but when you have issues with it, your going to be the one on the phone with Dish talking to tech support in the Philippines and fighting over wether or not you should have to pay for a service call to fix it.
Unless the wire is In the wall and replacing it would be wrapping the house from the outside, I would make the tech replace it.
If you want to end a potential argument, take out the wire before the installer comes back and they have no choice but to replace it.
If the installer complains, tell him you called Dish and they said RG59 would not work.