"Deal with" == "Not blow up" == "No RUD" in the event of a single engine failure.
Manned space flight kind of has this kind of important additional requirement that things like ICBMs don't, which is that they can't just "go up" the have to come back down and not end in a ball of fire.
Unless I am much mistaken what what blew up was a first stage, not a manned stage. I do not believe that SpaceX plans on doing suicide burns to retrieve humans from flight.
What blew up is the second stage, the stage that would contain the astronauts. If this landing profile is also the profile they will use for a manned starship is unknown.
It feels to me like there is no backup plan for engine failures, but they can take so many paths here that I don't think anyone knows except people within SpaceX.
Example paths:
* Don't launch it with people until it has landed unmanned so frequently that everyone trusts it.
* Land cargo versions like this to get max payload, while manned versions light a lot sooner, with possibly more engines, and sacrifice some fuel for increased reliability.
* Catch starship just like the booster in case of failure, with a longer travel to support higher speeds and lower G's.
* Add a parachute or increase the flap sizes to lower terminal speed so much that it is survivable to land without engines.
The test articles for the first stage are still being built and are expected to land similar to the falcon 9, which the big difference that Elon is talking about them being catched by a tower instead of landing on their own legs. This seems far enough away though that I would not be surprised if that changes radically.
Manned space flight kind of has this kind of important additional requirement that things like ICBMs don't, which is that they can't just "go up" the have to come back down and not end in a ball of fire.