He allowed it- He allows man to do whatever they wish because that is what free will is- Some will use free will wisely, some like the cowardly scum that did 9/11 attacks abuse free will to the detriment of mankind-
Let me rephrase that- He allows man to do ALMOST whatever they wish- God does intervene in some cases- However, man decided he wanted death and destruction rather than obey God’s orders, and so God allowed him that choice since man has free will- He even allowed the angels and Satan free will and some rebelled-
God allows man to suffer the consequences of sin- He wanted us NOT to eat of the fruit- He warned us- but we ignored him (and yes- Everyone one of us would have made the same choice because sin has an allure to it- but the possibility for choosing sin had to be there in order for free will to be a reality-)
We Still however have free will and what matters NOW is- Do we accept Him and His Son as Savior? Or do we get angry and reject Him because we think the effects of sin is unfair? Do we get on our own moral high horse and accuse God of being morally unfair? Or do we humble ourselves and accept His word?
He has provided a way of escape to ALL who turn to Him- but it must be doen in a free will choice- still to this day-