No, that will not work for him. He would need to be on title as one of the owners of the property
This is NOT legal advice, just a general discussion of the law, as we are not familiar with the specific documents and facts of your case, etc. Please consult with a competent attorney in this area of the law for specific legal advice regarding your particular case, as the advice may vary depending on the facts.
If the building contractor was not licensed to perform the work, then unless the contractor comes within the very narrow exceptions, the contractor will be entitled to refund all money collected and barred from making any claim for money owed, even for materials. Business and Professional Code 7031(a)(b). Matters of proof are very difficult to evaluate without the proof. Someone would have to hear the testimony of the witnesses and look at the surrounding documentation to evaluate it. Hopefully, there are at least some emails confirming the nature of the relationship as well as evidence of payments demonstrating that the contractor was paid along the way and not a partner.
The contractor has a difficult burden of trying to prove the existence of a "Partnership Agreement". Examples below:
Can he show any evidence of what consideration he was to receive for acting as your "partner" (example: is there an agreement to sell your property and divide the proceeds, or were you at all times intending to stay/reside at the property ) ? If there was no agreement for the division of "profits" from the partnership endeavor then he can't meet his burden.
Can you show that he was being reimbursed for all materials and services in a normal course (example: he invoices you for the materials and his labor and you pay in full) ? If he is being paid for all of his work, then his burden is not met.
In summary - people sue for all sorts of "bad" reasons, and this contractor may try and sue you despite the unavailability of supportive facts. However, you'll want to hire an attorney in anticipation of a possible lawsuit and send a "Demand Letter" that he cease and desist any conduct that you want to stop.
Best of luck. Jim Greer
JAMES GREER is an attorney with offices in Del Mar CA and Boulder CO, practicing in the areas of Real Estate, Business, Construction Law (858.481.9006) (jamesgreer@CalCoLaw.com) Please understand, by way of disclaimer, that any response provided to your AVVO question does not mature into an attorney-client relationship and you are always advised to seek out a local attorney so that all of your information can be conveyed and responded to appropriately.