After looking through the libp2p's kademlia implementation and their outdated kademlia specs, it seems like peers aren't stored on an LRU-ordering basis. Discv5 requires that peers be stored on an LRU-ordering basis for that least-recently seen peers can automatically be removed from the routing table.
After asking in the libp2p IRC channel, the routing table in js-kad-dht stores and removes peers on a least-recently-used basis. No changes need to be done.
After looking through the libp2p's kademlia implementation and their outdated kademlia specs, it seems like peers aren't stored on an LRU-ordering basis. Discv5 requires that peers be stored on an LRU-ordering basis for that least-recently seen peers can automatically be removed from the routing table.