He probably wants some time to consider as well as to call the Tennessee staff. Apparently, his family is pretty squared away and likely would want to notify them directly rather than have them learn from a post on a recruiting site. Any coach would want the same courtesy. I surmise that the Tennessee staff realize they have a challenge holding Santos considering his Texas connections and having been a Longhorn fan all his life. Had Texas offered 10 months ago, he likely would have committed on the spot.
I can't blame these kids for changing their minds. Most 17 and 18 kids know diddly squat about the world and verbally committing to play football for a school is not akin to signing a blood oath, particularly when the coaches bail all the time, as we saw at Rutgers this week.