[grotesqueness]

Then why he still told them not to eat it despite knowing that they will for sure eat it?

the correct question is not about God knows the answer a not

the correct question is why adam and eves disobey God

God created many things
but He only gives adam and eves a choice

did God give other creation  the same choices like he give to adam and eves

God did not gives the same choices to other of his creation like he give to adam and eves

God give adam and eves a choice
God only give them a option
God never give those options to others of His creation

that is the purpose of adam and eves and their offspring creation