Be confused with setup time slack calculation

The uTsu is subtracted from the Data Required time. You seem to have a negative uTsu value in the case you show. Thus, Required = 10.254 - -40ps = 10.294. Most often you will see the uTsu subtracted in the TimeQuest reports.

+----------------------------------------------------------------------------------+

; Data Required Path ;

+-------+--------+----+------+--------+------------------+-------------------------+

; Total ; Incr ; RF ; Type ; Fanout ; Location ; Element ;

+-------+--------+----+------+--------+------------------+-------------------------+

; 2.500 ; 2.500 ; ; ; ; ; latch edge time ;

; 2.500 ; 0.000 ; ; ; ; ; source latency ;

; 2.500 ; 0.000 ; ; ; 1 ; PIN_L22 ; clk ;

...

; 4.910 ; 0.000 ; ; ; ; ; clock uncertainty ;

; 4.831 ; -0.079 ; ; uTsu ; 1 ; FF_X52_Y24_N29 ; out_reg[6][7] ;

+-------+--------+----+------+--------+------------------+-------------------------+