I can't currently find the reference to the insorum variant attack in the past, but if i'm remembering correctly it's in the archived newsfeed...
still, let's look at the facts.
Insorum was used across several constellations, in an effort to remove the slave populations.
it was used on both planets and stations.
the attack with the variant bioweapon caused massive and almost immediate casualties.
not one report has surfaced of a planet or station where insorum-based poisoning occurred on a massive scale, or even on a limited scale.
This kind of news is something the Empire would surely have broadcast far and wide, considering the huge amount of bad press they got for using Vitoxin in the first place. Yet still, not a single report...
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As far as I can see, as there have been no reports of massive mutation and death caused by Insorum use in over 5 years, it is definitely safe to assume that there hasn't been massive mutation and death.
while it may seem 'too easy' to make it harmless, there were no definitive statements that claimed it definitely was fatal or even harmful to those not infected with Vitoxin. 'believed to be' does not equate to 'is'
As the only evidence we have to go on is the events of TEA, which are still canon, even if CCP are trying to negate any lasting effects of TonyG's work, the only conclusion that it is logical to come to, is that VILAMO saw the possible problem and, being a drone with purely logical reasoning, managed to nullify the potentially harmful aspects of insorum, creating a version that performed the specific task it was told to design it for.
It was apparent that VILAMO knew that it was to be used to negate Vitoxin, to be used on planets, stations and in armaments, (so it would effect ship crews as well), as it would therefore affect those who were not infected, and some of those would be slaves that were to be repatriated, it makes sense that VILAMO would, to ensure that those slaves did not die from the effects of their rescue, remove the potentially fatal aspect, in effect engineering a retrovirus that only sought out the Vitoxin, and would otherwise be harmless.
I just can't see how it could logically be stated that the insorum used on the planets and stations in question, Kor-Azor prime, Sarum prime, and the entire ammatar mandate included, would have been fatal to the uninfected, simply put, we'd have heard something... from both the Empire, and the Republic.
Consider how many voices would have been raised in either concern or victory, if the vast majority of nefantar suddenly started dropping dead after the repatriation, or if the entire amarrian population of two of the house core-worlds and many other planets and stations had done so?
is it an assumption? yes.
but one based on a massive lack of evidence to the contrary.
Those who would have been dead if you are right, are still alive.