NYPD has a much bigger anti-terror capability and has Times Square covered. I doubt they could have gotten away with anything
“Gotten Away”? Yes, they likely would have been caught... BUT - I doubt it would have been all that difficult to drop a backpack and walk away, dial a cell # and boom. Literally less than 1 minute operation.
Yes - there is security and surveillance - but when one only needs seconds... The authorities are minutes away.