What approach? Negotiating a contract before signing it. The only potential problem I see is that is that he didn't say that he had a representative from the company also initial the modification, and doesn't necessarily have a paper trail documenting that he informed them of the modification.
One of my employers even had a process in place where you submit things you do off work or plan todo and you can officially get these approved before signing, like running a side business, etc. Its a contract, so its negotiable. HR likes to create the impression it's a static document, but it's not. Future employees have a lot of underleveraged negotiation powers, especially at large companies I think.