Relative clauses

Hi everyone.
Why is there one answer to the following clauses?
* 1.The man stole the money. He must be punished.
=The man who stole the money must be punidhed.( one answer /textbook)
Can we say it like this:
The man who must be punished stole the money.
I mean, does this have to deal with cause and effect or what?
2.The novel won the first prize. It pleased many writers.
= The novel, which pleased many writers, won the first prize.
* Why is it a non-defining relative clause?
I think the information of the relative clause is essential.
Thanks in advance