BOLT07: prune if oldest channel_update is > 2 weeks old

07-routing-gossip.md

@@ -981,7 +981,7 @@ A node:
 #### Requirements
 
 A node:
-  - if a channel's latest `channel_update`s `timestamp` is older than two weeks
+  - if a channel's oldest `channel_update`s `timestamp` is older than two weeks
   (1209600 seconds):
     - MAY prune the channel.
     - MAY ignore the channel.
@@ -999,6 +999,11 @@ unlikely to be part of a computed route, since they would be partitioned off
 from the rest of the network; however, they would remain in the local network
 view would be forwarded to other peers indefinitely.
 
+The oldest `channel_update` is used to prune the channel since both sides need
+to be active in order for the channel to be usable. Doing so prunes channels
+even if one side continues to send fresh `channel_update`s but the other node
+has disappeared.
+
 ## Recommendations for Routing
 
 When calculating a route for an HTLC, both the `cltv_expiry_delta` and the fee