The Fermi paradox includes us knowing a lot about the density of stuff in the visible universe. You'd expect expansionistic life to populate most of a galaxy in short order since there are only the three dimensions to expand in. The Everett multiverse is a bit bigger. Would you still get a similar expansion model for a difficult to discover cheat, or could we end up with effects only observable in a minuscule fraction of all branches even if a cheat was possible, but was difficult enough to discover?