WWE originally took the title off of Cena because most of their male adult demographic had been booing him, however didn’t want to turn him heel because of how much merchandise he moves and the fact that the child and female demographics love him.
There are several indications that there is nothing behind these rumors however, one being that it is extremely hard to splice in old footage into a live broadcast without anyone noticing. Another is that WWE probably wouldn’t have put the title back on Cena if they thought people were going to boo him, however as we all know, WWE does a lot of things that may not make sense to us.
It is still unknown whether Cena knows about this or, if it is true, whose decision it was.
WWE did recently do this for the clip of Candice Michelle on The Tonight Show that they added to their website.