Considering this is 3 centuries later, Ordo's desires are now a part of history and have gone by the wayside so far as relevance, especially considering the sith are suspected to have infiltrated the Mandalorians' ranks by this point and using the mandos as puppets.
They had allied with Exar Kun's sith and received "the short end of the stick" so to speak (bad deal).
It had not originally been their idea to attack the republic in the first place, they were rather manipulated/bribed/in some way convinced to do it. By the dromud kaas sith who then sealed themselves away.
Revan set Ordo to unite the mando clans and restore their honor.
Mandos aren't particularly happy with the republic after Revan's departure. Though they wouldn't ally with the sith either.
So far as honor, best we can glean from Canderous was that it was battling and warring with strong enemies. By the emergence of the sith 300 years after Revan, Canderous Ordo is long dead, the Republic has been at peace and had been recovering. It's understandable the mandalorians would get a little stir crazy. Unaware of sith infiltrations, the mandos could be persuaded relatively easy once their leadership and power structure had been usurped. Though I get the tugging sensation that not all of the mandalorians were blind to what was going on; some were indifferent, some liked the idea despite it being historically foolhardy, others didn't like it. A good chunk of TOR's story will probably be about the split and ensuing infighting of the mandalorians.
This premise does set up the tone for why, so many years down the line, mandalorians are disliked by the republic. Though those who remain and follow the code of honor, doubtless that of Canderous Ordo's, still have that honor.
We'll murder them all, amid laughter and merriment...except for the few we take home to experiment!
"I cant see S***! --YOU GO TO HELL!" --Tourettes guy