Not long after the Gatecrash Prerelease, I posted the following question and I got answers. Please see that thread here:

http://community.wizards.com/go/thread/view/75842/29748767/Evolve_without_the_new_creature

Part of me still isn't comfortable that the rules work this way. I understand effects like Consuming Vapors, where you first get rid of something and then ask about its characteristics–you're going to have to look at its last known information. But why do we do that with intervening “if” clauses? The whole point is to see if the condition is still true on resolution, so it's weird to me that creatures with Evolve could still get a +1/+1 counter, even if the new creature was Murdered while players had priority.

In a similar situation, I was explaining to another player that same day about Biovisionary. I had told him that after the trigger condition is met and goes on the stack, that if a player Murdered one of the biovisionaries when he had priority, the condition would not be true on resolution and the game would not be automatically won. This, however, is a true example because although name is a characteristic, the condition is that the player must control four or more creatures with that name.

Sigil Captain works similarly as Evolve, since the creature doesn't need to still be on the battlefield when it resolves–it just needed to be 1/1 when its last information is checked.

So, I'm wondering: would it be a good idea to even suggest to the rules templating forum that with triggered abilities involving intervening “if” clauses, that the whole condition must be true on resolution, meaning the creature should still be in the zone it triggered from?

Just realized that Sigil Captain was a really bad example. Let me search Gatherer for a better one.

608.2g If an effect requires information from the game (such as the number of creatures on the battlefield), the answer is determined only once, when the effect is applied. If the effect requires information from a specific object, including the source of the ability itself or a target that’s become illegal, the effect uses the current information of that object if it’s in the public zone it was expected to be in; if it’s no longer in that zone, or if the effect has moved it from a public zone to a hidden zone, the effect uses the object’s last known information. See rule 112.7a. If an ability states that an object does something, it’s the object as it exists—or as it most recently existed— that does it, not the ability.

The intervening if clause in evolve refers to the specific object therefore LKI is applicable.
With Biovisionary, the if clause merely asks if 4+ creatures named Biovisionary exist under your control on the field, it isn't referring to any specific object.

I suppose it gets weird when killing the entering creature with Murder achieves nothing, but killing it with Tragic Slip (-13/-13) succeeds in thwarting the condition.