Why were so few of the River lords sent to the Wall after the RW?

[Oakhearts head]

It just seems strange from an in-universe perspective. From the Crown's perspective, with Renly Baratheon, Balon Greyjoy and Robb Stark now dead and Stannis defeated on the Blackwater, for all intents and purposes the War of the Five Kings was over. Despite this, only Desmond Grell and Robin Ryger voluntarily join the Night's Watch, and Blackfish is apparently one of the select few from the Riverlands who were going to be sent up there. Sending the lords of the losing side to the Wall is a pretty typical sentence in Westeros, yet Jason Mallister, Tytos Blackwood, Karyl Vance, Jonos Bracken and others were all pardoned. Is there any explanation whatsoever for this in the books?

[Ser Scott Malkinson]

There are a few reasons for that:

1. The Riverlords were offered a full pardon if they would stop fighting. Since most did there was no need to send them to the wall.

2. The Lannisters can keep them in check because they have hostages from the Red Wedding. Edmure Tully, Marq Piper, Patrek Mallister and probably others as well could be executed if the Riverlords were to rise up.

3. Jon Snow is Lord Commander of the Night's Watch. Since the Lannisters see him as an enemy, it would not be wise to send other enemies to join him an possibly give him the army he needs to rise up against the Lannisters.

[Trigger Warning]

" when your enemies defy you, you must serve them steel and fire. When they go to their knees, however, you must help them back to their feet. Elsewise no man will ever bend the knee to you."

Grell and Ryger volunteered for the Wall as well, having lost their positions in the Tully household at Riverrun.