Heroes and units are “cards” though. There are specific rules about cards leaving play area, i.e. “Cards have no memory”.
Tech buildings / Tech levels are not cards. Card-specific rules don’t necessary apply to them.
I.e. I can see logic behind
“Injunction makes inoperable not just Tech I building, but “Tech I” as a whole. You cannot do anything related to Tech I building at all while Injunction effect is active”.
Also please stop trying to draw parallels between “Disabling” units/heroes and “Disabling” Tech building via Injunction. Injunction makes building “not operational”, as clarified by italic text. It’s unique mechanic.
Yeah, I’d love to see @sharpobject 's take on this =\
I also suppose that a player can rebuild Injunctioned and destroyed Tech building, but not for reasons you state. Rather, for a reason that disabling a Tech building for two turns in a row with a single attack is probably too powerful.