I think the point is that anybody is theoretically capable of beating anybody else if you assume they can do a clearly better job in all respects. You could replace "GM" with any other entity without making it more or less true, because the statement is so firmly rooted outside of reality.
If there's a practical path to GM doing the same things Tesla is doing that's in line with GM's observed practices and capabilities, that would be much more interesting — but the fact that Bizarro World GM could beat Earth-1 Tesla doesn't tell us much of anything.