When Dylan infects the main characters, Jill is the only person who isn’t infected. Dylan says that this is so she can watch her comrades die, but there’s actually a more practical reason for why he chose to not infect her. Jill has already been infected with the T-Virus, and Wesker created Uruboros from the T-Virus antibodies in her body. Because of this, there is a high probability that Jill would be immune to Dylan’s virus. So Dylan didn’t bother trying to infect her because he wouldn’t have known if it would work.
The main characters manage to fight off the virus for so long compared to others because Dylan most likely gives them a weaker dose to keep them alive long enough for his monologue.
Why isn't Rebecca included in Dylan's game? She's no longer a field agent and spends most of her time as a doctor making cures, so Dylan probably considers her someone who's doing actually valuable works.
Given BSAA's eventual corruption in Resident Evil Village, Terra Save's higher-up being a secret terrorist and the U.S government's history in dealing with bioweapons, Dylan is perfectly on the nose about the heroes only protecting the same people who cause everything to happen in the first place.
