If Knowledge is disabled, the trader won't sell techs. Take a look at the Nemesis scenario as example.


Depending on what you plan to do this might become handy.
It has some nasty side effects, as it disables Knowledge [Skilltree, Knowledge Overview - killed animals - built structures ....]

However, you can alter Gameplayflags during runtime (switch from false to true), might be possible for Features too.

Good Luck!