What the Hell does that have to do with what I said? No, really, I want to hear it.

: Seriously though, he might not have known what it was,

Luminaries.
They're these nifty little sensors that can locate humans and discern an advanced AI from all the other electronics on Harvest, and they can do this from across a solar system.
And these are the inferior Covenant-built copies.

So yes. The defenses were firing back at the Chief when he was doing the trench run. If Forerunner technology is all it's cracked up to be, we can assume that the defenses were scanning the Chief. If we go by Greg Bear's novels, we can assume that ancilla in Didact's ship and Collector armor were keeping him up to speed on the UNSC fighter blasting through the ship's pathetic excuse for defense turrets.

And once the Chief was on the ship, and the Promethean Knights were reporting that there was boarding action, the Didact would have scanned the Chief, if only to figure out what witchcraft his wife did to make the Chief immune to the Composer.

: since always

Since crappy writing.

: What about the part about the slipspace rupture right after that? How about
: after that when the whole core was falling apart?

"You expect me to outrun a slipspace rupture and a localized earthquake?"
"No, Master Chief. I expect you to die."

: I figured he was busy. Like you said, he's more of a commander. We have the
: saying "If you want something done right, do it yourself", but
: who's to say the Forerunners did, or saw things that way?

"The definition of insanity is doing the same thing over and over again and expecting different results"
I'm not saying that the Didact himself should have gone onto the field, I'm saying that it's ridiculous to think that the Didact was trying to stop the Chief with Promethean Knights, because they were scarcely an obstacle.

There were other ways he tried to stop us, but it barely registered on the radar. Like when he dropped that bridge out from in front of us. It hardly even forced us to detour!