What matters depends on one's goal.
Curiosity is a goal unto itself, so if one is curious, in that sense it matters.
If one is strictly limiting oneself to determining if the guy was behaving as a complete a-hole or not, one does not have to know the party affiliation; for even if he were only pretending to be racist as some kind of political false flag stunt, he was still being a complete a-hole.
Or maybe one is not curious about it at all, in which case for their purposes not even that matters. But that hardly means it has no meaning in the broadest sense. But here we run into an equivocation in the word "meaning" that depends on what philosophy of meaning one holds.
But I suspect, and maybe you can clarify, you mean it ought not be looked at through the filter of political alliance, as it is inevitable that there will be some a-hole's in any political party. But, sadly, in the times we live in, this hope is in vain. The Left has been pushing a narrative of the right wing as racist a-holes for decades, and even committing hoax hate crimes quite often. It therefore matters if this was a false flag operation or not.
The exercise of determining an accused criminal’s political leanings is futile and, unless it is specially a political crime, has no reflection on others who may share their political philosophy.
For example, the 19 year old money in Texas you recently murdered her two babies by leaving them in her car for 15 hours has posts on her Facebook page that are critical of Hillary Clinton.
Her action action of murdering her kids had noting to do with her political philosophy and in no way reflects on people who may share her political philosophy.