The other option would be to kick stipe out of a fight that he already had a full camp for and waited for like a year for. Either that or strip Jones.
Both of which would probably get far more backlash, especially since Tom is a relative newcomer with one big win under his belt.
Having precedence over 2 legends of the sport with a decade of seniority over him would be odd.
If Tom had been around before the Stipe bout was made, then I think the logic would hold up. Tom would be the obvious next in line.
Since they had this fight contractually signed before Tom came into the title picture, only thing that makes sense is they see it through.