I'd prefer Kagi's ability to kick in as soon as you declare the Target Lock action. You'd never even bother measuring to the original target.

What I'd really prefer is for Kagi's ability to read more like:

"Enemy ships within range 1-3 of you are unable to acquire target locks on other friendly ships."

That would make Kagi's ability work on all sources of target locks and make him a priority target against a lot of lists.