This is purely speculative, but it looks like there are two things going on here.
First, the explosion-washout problem doesn't seem to apply to AI vessels.
Second, based on what I can remember about what LW has said about AIs classifying and engaging contacts in DW, classification is a very on-off issue. There isn't any in between from "no idea" to "posID," and there probably isn't a "progress bar" to go from one to the other. In a normal scenario, the amount of time needed to get ID is probably abstracted from range. The contact will be detected at one range, and be classified (and engaged) some time later--after it gets closer. Because your opponent spawned so close, this all happened instantaneously.
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