Here's the deal: When I checked the "researched" flag in tech.dat for Lockdown, I still had to research it. When I unchecked it for Dark Swarm, I still DIDN'T need to. So I think it might actually be unused...
I think...maybe it sets the default option in StarEdit?
Will check.
EDIT: No, doesn't even seem to do that. Hm. Will someone else please verify this?
Did you alter the in-map settings for these techs?
No, I just started a Melee game.
EDIT:
Interesting...what ACTUALLY controls whether techs are enabled from the start or not is found in "Tech Use Requirements" in Mem(/Star)Graft. It appears that the "researched" flag is actually unused--although of course I'd like someone else to verify that.