User blog comment:Tachikaze Master/So I noticed something.../@comment-11372432-20150407090335/@comment-26069426-20150407161033

It makes sense that it works. Shadow Dive proves that the player is always present on the field, even if a monster is in the center position. The only time an attack is invalidated is when the monster is no longer present. So if we focus just on field presence as qualification for a valid target, calling Sleipnir does not change the player's field presence.

It reduces Sleipnir's utility, but it's still valuable in other situations.