I didn't want to hijack the thread on orbital bombardment, but have wondered why Merlin couldn't use Zion as a test bed for forbidden tech. Obviously some things, like steam power, might be hard to hide from the church, but I think radio or electric power generation might be feasible to test in Zion without being noticed by the locals (including the authorities).
If the orbital bombardment system were to react to tests like this, how would that hurt the progress of the war? Yes, there are likely "innocent civilians" in and around Zion who would be zapped by any bombardment, but the demoralizing effect of having God's wrath fall on the church leadership in Zion could end the war more quickly and save even more lives elsewhere.
However I would be willing to guess that there is a very good chance there is a cache of technological goodies and/or data and information under the temple. If you nuke the temple or trick the OBS into bombarding it, then all that stuff is gone. I'd say it is much better to capture the temple and use all that stuff to help Safehold return to the stars.