What should connect them, except only the external factor that they are published by the same studio? Completely different game universes.

^^ yeah. Easter eggs and the like are often taken too seriously by fans, in my opinion. Sometimes it’s a coincidental thing that was implemented for the purposes of referencing another franchise, not to connect universes.

For example, The Witcher 2: Assassin’s of Kings has a dead man in an Assassin costume from the Assassin’s Creed franchise. Doesn’t mean those two franchises share the same universe - they very obviously don’t.

Now I'm just saying that they are in the same universe for the sake of the joke.