Where can I get some of whatever this scientist has been using? :lol:
Now, trying to be serious:
how can you ever create a genetically healthy population? Most mammal species need thousands of individuals to make sure that inbreeding doesn't become fatal in the long term.
Even if you use Elephant DNA to fill in the gaps in our knowledge of Mammoth DNA, you end up not only with the genetic defects of the Mammoth 'parents' you used, but also with a whole load of incompatibilities between DNA of the two species. It is like taking source code files from two completely different versions of a piece of software, trying to combine them into a single software build, and expecting it to be bug-free.
I think that for all the patching, more needs to be know about the biochemistry of Elephants AND Mammoths than we currently know about any species (except maybe for some simple bacteria and viruses).