But that doesn't prove that he had a sin nature. Sin nature is a having a spirit that is separated from GOD (spiritual death). Christ never had that.
3 Without father, without mother, without descent, having neither beginning of days, nor end of life; but made like unto the Son of God; abideth a priest continually.Hebrew 7
His corrupted flesh as that seen was used for a one time demonstration of the work of His unsen Spirit poring out his Spirit as if it was literal blood . Of that flesh the Son of man declared it profits for nothing .When the one time demonstration ended he gave us a clear warning not to be faithless as Thomas who he used as a example of "no faith" .the evil generation of natural unconverted man kind.
No fleshly Jesus we walk by faith (the unseen eternal) not by sight as that seen the temporal
Wherefore henceforth know we no man after the flesh: yea, though we have known Christ after the flesh, yet now henceforth know we him no more. Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.2 Corinthians 5:16-17
Ask one self how much more ? The veil is rent.The antichrists as those who glory in the things seen need more in order to go above that which is written.