#3 He isn’t in a position for such a high-profile win
When Velasquez made his WWE debut during the FOX premiere of SmackDown, he gained quite a lot of momentum. His association with Rey Mysterio and the attack on Brock Lesnar that sent the WWE Champion running cemented him as a big threat to The Beast. However, after a tap-out defeat in 2-minutes' time at Crown Jewel and his subsequent disappearance from television, he has no momentum whatsoever.
We know that Royal Rumble is one of the most exciting pay-per-views of the year and the fans may be extremely unwelcoming of a former UFC Champion winning the battle royal unless he proves that deserves it, both in storyline and reality. Velasquez has only wrestled one match for WWE and it wouldn't likely be a wise move to have him win the Royal Rumble match this early in his run, especially if he's only going to be working on a part-time basis. WWE has to build his character first before giving him such a huge victory. Although it is possible that Velasquez will be one of the final remaining Superstars at the end of the match, chances are that he would get eliminated only by someone who’s more valuable than him to WWE, be it a rising star like Drew McIntyre or even Brock Lesnar himself.