If it were physical death, the God would be a liar, for Adam did not physically die on the day he ate the forbidden fruit. Doesn't say that he would....
Genesis 2:16-18
(KJV) 16 And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat: 17 But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.
(NIV)
16 And the LORD God commanded the man, "You are free to eat from any tree in the garden; 17 but you must not eat from the tree of the knowledge of good and evil, for when you eat of it you will surely die."
(New Living Translation)
16 But the LORD God gave him this warning: "You may freely eat any fruit in the garden 17 except fruit from the tree of the knowledge of good and evil. If you eat of its fruit, you will surely die."
The TIMING of the eating seems to be a bit fuzzy, but the SURETY of death is clear!
Doesn't say that he would.... Sheesh. The very same text you posted refutes you:
for in the day that thou eatest thereof thou shalt surely die.