He wasn't trespassing when he was shot.
That said, I may be misremembering, but it seemed I saw a video that made it look like he was in someone's house undergoing a remodel in an already developed neighborhood. That's akin to me finding someone poking around out in my shop simply because the rollup door was open. That is a "my gun is already out" situation, especially where I live, where there is no help for me readily available. Not that I would come out guns blazing, but I would be in condition orange with my gun visible while I question/assess from a distance.
If he was in an in-progress housing development that was under construction, while I'm sure the "trespassing philosophy" varies geographically, I know that a lot of people do what Millcreek mentioned. While I assume that is still trespassing in the letter of the law, it may or may not be looked at as trespassing by various individuals affected. The homebuilder may look at it as "advertising" regarding what Millcreek did, but would still consider kids playing in the unfinished homes trespassing.