That's a very specific mod. I am not aware of such a mod existing.

Maybe because, that would be something completely different than what I was hoping to find? I was pretty clear that I hoping to find something that slows down the AI basically having this rather critical tech basically right from the start. Taking it away entirely, would be likely be a lot simpler, but that is not the goal. I just want something that makes it more far more expensive and time consuming for the AI, to get their mitts on, and hey, if it applies to the player, Id be ok with that too.  

I suppose it would be possible to seriously ramp up the cost, and its location in the tech-tree, but Im not really currently conversant with modding this game atm.

Planetary invasion is kind of a game changer, and I say this as someone who has experienced my HW being captured by the AI within less than an hour of gameplay on more than a few occasions,  often accompanied by escorts I cannot hope to match, much less defeat.  

Just base game, gigantic. Its pretty much always the usual suspects, Krynn, Yor, Drengin etc, since I almost always pick up pragmatic and benevolent, so, they pretty much guarantees they will declare war almost as soon as you make contact. My beef with this, is how all the factions seem to come pre-equiped with Planetary Invasion tech, thus my hoping to find a mod that moves it far....far  up the tech-tree. That way, they can still declare war, attack shipping, bases etc, and generally be a nuisance, but, cant end the game before it even gets started.

Make a copy of MasterTechDefs and place it in ....Documents\My Games\GC3 Crusade\Mods\Example Mod\Game, Open MasterTechDefs in a text editor, search for PlanetaryInvasion, set the Weights, yes all of them, to 0, save the file. Now the AI should (Unless there is back round hardcode) ignore this tech untill it has no options but to take it or you sell it to them. (Requires a new game)

Yas, or they require a tech in the same branch and Planetary Invasion is on route. Slim to Zero chance the AI will research it. Some AI start with this tech though, and it is tradeable.