Protein denaturation happens because the tertiary structure is broken as the charged and polar interactions of each residue are broken or disrupted. Salt will have little impact on the peptide bond.

Death due to salinity is usually due to organisms being unable to maintain a proper intracellular osmotic balance rather than from direct protein denaturation.

Hypersaline solutions may cause some of the DNA to precipitate, however I'm not sure if it will have a net negative, or net positive effect. I'm actually leaning towards it possibly having a protective effect, but I'm not sure I have the background in biochemistry necessary to say that from a position of authority.

Overall though I expect it would be unlikely to make any measurable change to the numbers listed above, especially since the calculated half life was for samples that were buried and are therefore surrounded by a lot of minerals as well, and therefore also likely salts. I'm guessing any protective effect from our example would be insignificant.

Edit: Here is an article that does suggest high salt concentrations have a net protective effect on DNA preservation in the environment, though the study does suffer from some major limitations so we are unable to conclude to what degree this would have relative to the paper I mentioned in my first post. I expect it might skew the half life to the longer end of the range, but to what degree I can't speculate.

https://www.nature.com/articles/srep22960