They really don't want it to blow up on the launch pad. They've put a lot of work into the ground service equipment, and depending on how bad the damage is, blo

They really don't want it to blow up on the launch pad. They've put a lot of work into the ground service equipment, and depending on how bad the damage is, blowing up on the pad could set them back months. It also isn't clear if they will have completely finished all the protections on the launch equipment (cladding, deluge, etc) before this test flight, so blowing up on the pad this time around might actually be worse than if it happened in some future test instead. Once it is well-clear of the pad – blowing up is a lot less bad. But still, ideally they want it to make at as far through the flight plan as possible. If it blows up early in the flight, there's a lot of stuff that happens later they won't even get the chance to test this time around. Sure, they'll get the chance to test it next time around – but that'll be another delay in an already delayed project.