Also it could be because the crowd would be burned out by that point and in their eyes Becky is more valuable than Rollins, so you gotta maximize the reactions.
Nia being in the Rumble was a mixed bag because while it was cool to see her actually do moves in Orton, Rey and Ali, the commentary and crowd feeling so happy about her getting a 3 on 1 beatdown was...... off-putting, to say the least.