I believe that Add downvote option to Low Quality Review Queue list of potential actions needs to be revisited.
When using the low-quality post review queue, there are three options for answers: looks ok, edit, or delete. More than once, I've run across an answer is most certainly not "ok" - it is not good as it is and it definitely is low-quality. However, I am unable to edit it because I don't have the knowledge necessary to fill in the missing details. However, deleting seems wrong because, even though it doesn't meet the community quality standards, it's minimally helpful and deleting would do a disservice.
It is possible to leave a comment and down-vote from the review queue, but that's not always the best option. Sometimes, the post is already at -3 or more downvotes and downvoting more feels like piling on. Especially if it's a newer user, that feels very unwelcoming. Leaving a comment is a good option, but there's still no way to progress onward without selecting a wrong choice in the options. It feels wrong to downvote and/or comment with how to improve while also saying that the post "looks good".
I'm not sure exactly what the solution looks like. One option is the one presented in the linked question. Another would be to remove the options entirely and let the reviewer use the tools visible in the post (voting, editing, commenting, deleting) in-line, and then saying either "done" (if any actions were taken) or "not low quality" (if no actions are needed), where the "done" option would be disabled unless at least one action was taken.