One legitimate objection could be that they vertically mix heat into the ocean more
efficiently than the observations support (Forest [2008], Hansen [2011], & Kuhlbrodt & Gregory [2012]-RRB-, i.e they have weaker - than - observed surface stratification - the black line bulge in Figure 3 (c) in the top 200 metres of ocean.
The best possible
observations of the detached layer are made in ultraviolet light because the small haze particles which populate this part of Titan's upper atmosphere scatter short wavelengths more
efficiently than longer visible or infrared wavelengths.