2 Things here.
1st.
If the contract he signed says to ask about such matters then it is not a issue with the contracted company.
As long as the contracted company says he can work at the other company then he is clear to get that part time job!
Keep in mind most companies who allow you to work a 2nd job require that your work at their company is not effected by your work at your part time job.
As long as the 2nd job does not conflict with your main jobs hours and is not a competitor in the companies eyes then they will most likely say its fine.
2nd.
To answer your question:
I have a feeling that this may be looked at as not a good thing in the new company. What do you think?
It is not something that would be looked down on. As long as what you do outside of work is not effecting your job then there is nothing to worry about. A company will be clear on their requirements for this kind of request.