It's possible that the Vex simulation was intended to learn more about the Warmind itself, one of the strategic goals of the Vex. It is logical that a simulation that acts with such precision would assume the conclusion to draw the incalculable into the equation. As Fragment Rasputin 2 states,
"And she wonders who won this battle, who learned the most, the Vex baiting out this new power, or the Cabal hunting it. Or the Warmind itself, testing its reborn strength."
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Just found this on a DB Card. "The Hive know the power of Rasputin, they've fought him on many fronts. But this attack seemed targeted. There was some kind of purpose in this, one that I can't seem to follow. You stopped them from tearing apart this arm of the Warmind, but perhaps Omnigul found what she sought. It’s not like her to run from a feast of Light." - Eris If the hive know of a warminds power why not the vex.
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The crazy thing is that the Vex are able to process so much information from so little interaction with anything. That is an interesting thought, maybe it was trying to figure out why the warminds are such a threat and the key to its powers.