DNA can prove someone was present at a location, it cannot prove that he wasn't.
If you can prove someone else was present, it creates reasonable doubt.
It doesn't mean the first person is innocent: it simply means they are unconvictable.
To "exonerate" is to prove someone innocent - which DNA evidence alone rarely does.
I agree with your point generally speaking. In this instance the DNA is as close to definitive as possible because it positively identified another man who just so happened to be a known sexual predator who had attacked another woman on the same beach a few years earlier.
Your logic is so weak as to be unbelievable. Based on your very strained logic, it’s possible you committed the crime.