Just exercise patience and continue negotiating until your client gets the key.

Lease-option agreements are our main exit strategy; they allow buyers to rent the property with an option to buy later, providing investors with cash now, monthly flow, and back-end profit when the resident exercises the option to purchase.

Chances are, the tenants will do a crappy job maintaining the house (they are renters at the heart of it all) which is one of the "benefits" and they also usually don't exercise the option to buy (so you don't get that inflated sales price you were planning on getting).

If you take any negative action against a tenant in response to them exercising their rights that would fall under "landlord retaliation".

You are only allowed to attempt to exercise your right to purchase once, and if something goes wrong your purchase right is nullified completely.IMO, in most cases it would take a great deal of appreciation over the course of your lease in order to make it worth paying the full right to purchase price of the house that Home Partners buys for you to rent. 

I'm just thinking I would be extremely cautious and exercise extreme due diligence if I personally went that route right now.If you acquired more properties yourself, directly, are you comfortable with renovations?

@Zach Edelman I would exercise great caution as it pertains to Waikiki and any other market on Oahu that is showing up as a great place to invest.

The best thing you can do is go through the exercise of a developers costs and exit strategy, target what they want to make on the deal, and then back out their profits to see where you need to price it.

Try a simple exercise with him of listing all the financial considerations and purchase/management activities that you can anticipate today - who will do what, who contributes what - consider putting all this in writing in some sort of operating agreement. 

That should come from the why.If you have not already done so read Anthony Robbins awaken the giant within and do the written exercises in the book .