"He needn't it" actually make sense? Y'know, "can't it". And you can argue "he haSn't it" otherwise.
Try to get what I mean here please. Since you can't say "can't it", which is a rule of the auxiliary verb, why do y'all say "he needn't it" all the time?

Question

"He needn't it" actually make sense? Y'know, "can't it". And you can argue "he haSn't it" otherwise.
Try to get what I mean here please. Since you can't say "can't it", which is a rule of the auxiliary verb, why do y'all say "he needn't it" all the time?

Answer

You can't say 'he can't it'

Answer

Hi,  you need to have more for these to make sense
 Example: "He needn't [ need not]  argue about it".
Y'know = you know. Example: You know, food is getting more expensive these days.
  Example: "Can't [ cannot it] it wait?  I am too busy to help you now". 
  Example: "He hasn't [ has not]  got what it takes to be a doctor."

Answer

Are you sure you have heard it correctly "he needn't it" ? 
You can say, He doesn't need it or "he needn't  do it" [ he need not do that]

Answer

No, it doesn't make sense. Maybe a few rednecks say "he needn't it", but otherwise I don't know.