For sure there are people behind this negotiation since they will not divert Casimero fight to another unexpected fighter without any reason and might they see the hype is so premature yet and they want to widespread the news about Inoue vs Casimero so that they can earn huge money for this match up. Casimero needs to win this so that he can bring more hype to close that fight against Inoue.
If I'm not mistaken, WBO just stepped in and ask a mandatory title defense because both Casimero and Inoue are just trading and exchanging tirades without even a 1% progress that their fight will happen soon. Casimero also leaks information that he will face Inoue last December which should not be disclosed until everything is official and under negotiation.
Moving forward, Casimero just needs to win this fight to have a chip at fighting Inoue this year. The return of the Monster is on June-July as per reports. Enough time for Casimero to rest if he wins in March.