Ok demon's child will be demon...means he will have all those powers he can use for evil...but if he is hukum's son he is Vish's son too...so if he is raised right by Vivi and Behir...he could turn out good...but if hukum snatches him away and raises him then he will be evil...so yeah Vish sentiment is right...but very risky...
U know in Supernatural there is Jack who is Lucifer's (devil) son...but his mom was a good human woman...when he was in her Everyone tried to abort him kill him... including the time she tried committing suicide...but he was born anyway and he is such a good character and now those same people who wanted him gone think of him like a son...So nothing is impossible...