It is clear and true that the History of the 3I is inspired by real history.
It is important to not conflate it as just real history pastiched over the setting; it isn't.
It's a whole cloth invention inspired by mixing and matching multiple historical situations and trends; Marc has made mention of the historical inspirations as just that: inspirations.
Further, as is shown in later games, most especially 2300, GDW doesn't just change the names on prior histories. They examine the situations, discuss them, pass them back and forth, come to consensus, and sometimes pick the less likely resolution as better story. Frank Chadwick has mentioned this in re both T2K and Space 1889 in the past. Dave N., likewise, mentioned this. Joe and Gary also have mentioned this; for them, the discussion of the storyline for MegaTraveller was clearly a group decision, not any one person's, but definitely subject to Marc's final sign-off. Marc has, for his part, repeatedly said of TNE, "The final decision was mine." From whence we get Virus.
Reducing it to the level of "Borrowed History" is a gross oversimplification. And quite unfair to the creative minds who formed GDW.