I have not been this too closely, but it seems that there have been two purposes for conservatives to use the Seth Rich story:

(1) The DNC was not actually hacked by the Russians and that it was really Seth Rich who leaked the emails. This argument seems to be completely discredited in the sense that there is now public Congressional testimony that the Russians did hack. Furthermore there is overwhelming bipartisan support for this. Thus this seems completely irrelevant.

(2) That the Clintons are evil and murder people. I guess this is still valid (if conspiracy theories are valid) but what would the Clinton's motivation be? This theory relied on the fact that Rich leaked to the Russians. Now that we know the Russians did hack the DNC, why would the Clintons want to kill Rich? I suppose it is possible that Seth Rich leaked AND the Russians hacked but this seems very unlikely.

Lastly, this is not really a "forensic" report in the sense of CSI or police forensic teams. As the report states, it had access to no police reports or examinations, and it examined the scene almost a year later.

Rather this is a report that makes the same kind of inferences from lack of data that the Seth Rich conspiracy has always used. It does cite some criminal justice research, but really at the bottom this report just proves that you can't prove a negative.

You can't prove that Clinton did not kill Seth Rich, becasue there are unanswered questions and strange behaviour based on reasonable inferences. This is what conspiracy theories thrive on.