if you were starting from just the DNA sequence and didn't really understand what the non-DNA context for them was or possibly even how the DNA helps produce the non-DNA context, you get a much less tractible problem.

I can't help but feel this is related to (what I perceive as) a vast overrating of the plausibility of uploading from cryonically-preserved brain remnants. It's late at night and I'm still woozy from finals, but it feels like someone who's discovered they enjoy, say, classical music without much grasp of music theory or even the knowledge of how to play any instruments figuring it can't be too hard to just brute-force a piano riff of, say, the fourth movement of Beethoven's 9th if they just figure out by listening which notes to play. The mistake being made is a subtler and yet more important one than simply underestimating the algorithmic complexity of the desired output.