I read in a different thread that the reason the other races would have a delay to speak with the player again was to prevent tech brokering abuse in GC2.  How about this solution which would allow the player to trade tech without abuse.

- When a civilization develops a tech, they have the copyright on it.   Only the civilization that developed it can offer it in a trade.  This way, a player can still trade his tech for alien tech, but the tech he obtained by the alien, cannot be used in a trade with another civilization.  Only the tech that he developed.

Unless you can negotiate a treaty with that race which lets you clone each other's tech.