Nagin et al, like virtually any government employee at the level of Town Councilman and above, is undoubtedly suspicious and frightened of the concept of receiving money via an honest and voluntary agreement.
Its the honest part tha has him stumped. If someone is offering him $100 per car, and willing to take up all the paper work and disposal issues for hazardous materials, there must be a catch or a really big profit.
Nagin can smell money and now he wants to analyze the situation, find someone else who can make a similar offer, give him a kick back or owe him a big favor, and give them the contract.
Instead, he should've split the city into sections and auctioned off the salvage rights for the vehicles in each sector. If they had a fair and open bidding process for most of the work that needs to be done in New Orleans a lot of what hasn't been done would already be done.
(But fair and open bidding for public projects doesn't lend itself to selling contracts for favors, contributions, and kick backs.)