SE usually doesn't let anyone flag an answer with high # of upvotes (such as the one below) as 'Very Low Quality' so how did this answer enter the review queue?
N.B. This discussion is not about the specific answer below which is now deleted.
As pointed out by Zanna in comment, when an answer is flagged as NAA (Not An Answer), it pushes the answer to Low quality review queue so that it is reviewed by privileged users.
1 The "not an answer" flag will trigger the answer to be reviewed by ordinary members of the site via the Low Quality Posts review queue if the answer has never been to that queue before.
It usually pushes an answer to the low-quality queue, where its fate is decided by reviewers. If it stays there for too long, the answer is also shown to diamond moderators in their flag queue. If the flag is considered valid, the post is deleted.
E.g the specific answer you've mentioned was flagged as Not an Answer.