He should be open shoving 66.
+1
I tried to think of table dynamics that would change this, but only a straight shove makes sense.
If the table has been playing tight, a shove wins the blinds a large portion of the time.
If the table has been playing looser, the calling range of those to act widens and improves our chances to win.
Also, +1 to raising smaller when the blinds get higher. If you raise to 2400 and get a caller, you only have a stack of around ~10k left and the pot can be as big as 6k - doesn't leave you with a lot of options for post-flop play. If you instead raise to 1800, you now have a pot of 5k with an 11k stack to work with.