Although traditoinal safeties don't get drafted in the top 10, CBs do.
Huff is not a pure safety.
He is good enough to play corner.
He provides the defense with an answer to the elite TE like Henry Jones did.
He can also provide coverage on slot receivers from the safety spot out of the base defense.
And in Marv's world, DBs are the one position that provide immediate productions from nickle formations and special teams, if he's not good enough to start (which is unlikely).