let me put it this way; if you had a player ask for a banshee with an assault cannon to materialize from the ether and smite their foes because their character wished real hard it would happen, would you go for that?
of course my players can run people over or blow things up. i'm very happy when they do that. but they have to go through the hoops of acquiring the vehicle or the plastique to do so, and typically they also have to smuggle the device past security or place their vehicle in an appropriate position to do so. mage just says, "hey, i'm bored, i got three seconds; let's summon the spiritual equivalent of an infantry fighting vehicle from nothingness!" sure, it's got a good chance of killing him, but he could do that anywhere. on a transcontinental flight, sitting next to a major megacorporate executive, whatever. security couldn't do anything to stop him if they don't have magicians handy*, and the fluff highly implies that they typically don't. it may not be the rational move, but it's an option. especially if you're not rational.
many people, including those who want to kill other people for political or religious reasons, are definitely irrational enough to do literally suicidal things. even if the summoner dies, there's a reasonable chance the thing he just manifested will go on a killing spree just as bad as the one he would have commanded it to undertake. so if you believe spirits should be as deadly as they are by the numbers, then you implicitly have justified the complete and total oppression of the awakened as walking weapons of mass destruction. because by any sane definition this level of power makes every reasonably powerful mage a suicide bomber that no chemsniffer or cyberware scanner can catch. security can't even figure out he would want to do it ahead of time if they didn't have a way to read his thoughts (so, more magic then). anybody who has the least possibility of being assassinated better have an astrally projecting top-tier mage on deck following them at all times who's ready to take life-threatening drain in a last-ditch banishing attempt at a second's notice. i'm sure that's cool for the president or damon knight to keep such dedicated professionals on staff, but everybody else must live in a puddle of fear and urine every time they leave their carefully warded fortresses.
folllowing this logic, how is the most rational response to this situation by the crushing majority of mundanes not just "geek the mage," but geek each and every mage sometime in the teen years shortly after magical abilities manifest but before said mages can become this powerful? even if that doesn't involve killing them, mandatory burnout of full magicians and conjurers wouldn't be out of the question as a "humane" solution to the mage problem. spirits like this are why there would be a magician holocaust sooner rather than later, and they're probably one of the major reasons everybody who's actually important lives in a mana void (e.g. orbit).
*i assume summoning something of this nature is probably a physically obvious action, but there's nothing in the rules that says it needs to be. furthermore, all you have to do is get close enough. mask your signature through the astral spotters, get a decent view of mr. president that's a bit out of the way of the security staff, and there's a good chance said security won't know what mage to geek before your summoned flying tank does its dirty work. can't even guarantee that a force 12 mana barrier will be enough to stop this kind of beast. elemental attack would pass through it as well, though i suppose the spirit would be firing blind through that. i would tend to rule that you can't make your spirit target anything you don't point out to the spirit astrally since it can't see the physical plane at all, so a dual-natured barrier might be a bit of a bugger to this plan. they better keep a mana barrier up around him every step he takes and around the vehicles in his motorcade though.
also, you could have suicide drones with real big shaped charges ready to go at all times in case this sort of thing manifests. in fact, i imagine three or four stealth-optics wih a couple kilos of plastique are probably hovering around a vip any time he's outside the enclave he calls home, along with the snipers with assault cannons in strategic locations. for that matter, i would imagine any corporate facility worth its salt has a couple of these drone bombers plus a steel lynx or two with an assault cannon handy. if mages have APC-level firepower on tap, you can bet that HTR teams show up with vehicle-killing weapons handy. all in all, just the potential of spirits of this potency being summoned means every force in the world is going to react with overwhelming force to each and every incident, just in case there's a crazy suicide-bomber mage involved.
