Am I right in thinking that once all the weapon platforms are dead the ship currently firing will continue to fire at the planet if it has unused weapons remaining, but any ships still to fire will not fire?
If so, a possible strategy is to create 'WP bombardment' ships that are very strongly shielded/armoured, but only carry a light armament. The light armament means that any one ship can only do a small amount of damage to the planet and shouldn't be able to glass it by accident.
On a similar topic, I wanted to throw my computer out the window the other day when my capture fleet descended upon a huge planet stocked with facilities, but instead of capturing it they glassed it. Meanwhile the troop transport dropped 500 troops on the nearby moon...
