Leighton Steward and Corbin Robertson are the creators of the particularly dim global warming denialist organizations CO2 is Green and Plants Need CO2. Their goal is to lobby against the classification of carbon dioxide as a pollutant; since it is a vital chemical for plant life, more of it can only be a good thing (since ... Steward and Robertson are plants?), and any reduction of carbon dioxide in the ecosystem can only be harmful. You don’t need to be particularly scientifically savvy to see the factual shortcomings of the strategy.
CO2 is Green has as its explicit aim to “educate” the public on the dangers of reduced carbon emissions, using adverts in several media. You can read more about the astoundingly stupid claims (targeted, it seems, at the Dunning-Kruger lowest quartile segment) they make here. They are also discussed here.
Leighton Steward (a short bio is available here) is the retired vice chairman of Burlington Resources oil and gas company; coal baron Corbin J, Robertson Jr. is the chief executive of Natural Resource Partners, a coal resourcing corporation (and is a frighteningly powerful guy – see for instance this). It does seem to be the case that Steward, at least, honestly thinks his arguments have merit, and he has produced some abysmally dumb ones. Steward nevertheless made it onto Inhofe’s list of “scientists” who allegedly reject antropogenic global warming.
Diagnosis: One would think they were dishonest, despite their ignorance, but at least Steward seems rather to be completely and abysmally ignorant and deluded. They are nevertheless dangerous, but there has to be a critical mass for the audience of this kind of silliness one hopes.