To encourage more prospects to finish their spring classes, the NFL doesn't allow a rookie to participate in team activities -- except for a team's three-day rookie minicamp -- until his spring semester's classes and final exams are completed.
The NFL rule applies whether the draft pick was enrolled for spring classes or not, so there's no incentive for draft hopefuls to drop out of classes.
X was at rookie minicamp, but missed 10 days of OTAs.
I'm not sure that missed time disqualifies him from taking some reps at RT -- he excelled as a T at UCLA, setting record for most starts on offense by a true freshman... 2012: started 14 games at LG but played some LT... 2013: started 7 games at LG and 7 games at LT winning Morris Award for best lineman in PAC12 and was UCLA's offensive MVP.
I think he has the classic OG body, but wouldn't be surprised to see him get reps at RT and even at C. He's a mature, serious young man.