I don't know about this specific user, but in general, yes:
We should be thankful for users who spend time downvoting.
If anything, we should have an alert for people who upvote far more often than they downvote. There is no shortage of well-meaning idiotsbut confused folks who upvote objectively poor posts out of sympathy (Oooh, somebody downvoted this new user's post, how dare they be so heartless! Oh, this rant gave me a laugh, let's upvote it!). Something needs to be done about these users because they make it difficult to clean up the site. Thankfully we have users who also take the time to downvote regularly.
If you have an issue about one specific user's actions, raise a custom moderator flag on one of their posts describing the issue in as much detail as you can.