Well, the Throne Agents have a locator beacon, so even though there are no scatter rules in Rites of Batttle the pod won't scatter. We're planning on planting the beacon on or near the target's guards, which are likely to be about a half dozen Tau power suits, like Broadsides or Crisis Suits, and a small contingent of Fire Warriors and/or Kroot. The GM said one fo the Astartes can make a Pilot Roll to try and hit something other than the locator beacon.
We're going to have to figure out things like the effect of a Drop Pod landing in a horde of Kroot. I feel like going by the fluff it should just decimate them brutally. Fire Warriors, due to their armor, might fare a little better.
And if we get it to hit something more sturdy like a Broadside, how much damage would it cause? A Drop Pod and a Broadside are both Enormous, and both have 30 wounds/ structure, but a Drop pod has 24 armor and a Broadside has 12. I guess you resolve it like ramming? That would probably be 2d10+24 to the Broadside, which I guess makes sense.
A drop pod WILL NOT hit an area of 20-40 meters wide with a battle-cannon type damage blast (5d10+20 or whatever). It'll cause a small indention in normal ground, flatten tall shruberies about 4-8 feet around it, and crash through a small house and maybe a few floors of a multistory building; all this mainly due to its weight.
A locator beacon is short range. Is your throne agent standing less than 25 feet from that broadside? Probably not anymore… well maybe his boots are still there…
It is a vehicle, a loud roaring and streaking vehicle which is very likely to appear on Tau radar screens… Its also firing quite powerful retro thrusters and using an anti-grav system to slow its decent before it hits. So its obviously not going supersonic when it lands. That and the machine spirit actually in control of the pod which is programmed only to land the device at pre-arranged coordinates doesn't really need help piloting a course with only 1 direction (down).
Then there's landing in the middle of a dozzen power suits… never a good idea. Unless of course your GM roleplays them as retarded power suits who have no ability to do anything other than stand still and make 1 standard attack a turn and not use any of the special abilities, talents, and rules which make them increadibly deadly.
Overall, I'm just saying you probably shouldn't be trying to turn a drop pod into a dedicated weapon. Some times a cigar is just a cigar.