Induction icing is not unheard of in the older M20K turbocharged Mooneys, but the conditions conducive to it are very cold temperatures in visible moisture and the icing forms on the induction air filter. Opening the alternate air system or descending into warmer air restores power. To alleviate the problem, the factory offered replacement automatically opening alternate air systems. The main region the reports of induction icing problems came from were in Northern Canada during the winter. There are no documented reports of induction icing problems in other areas, including those where carburettor icing is much more prevalent (such as IMC).
If the Mooney really was suffering from significant induction icing, the air supply would be being throttled and power output would consequently be low. I can't see how the pilot could then overboost the engine. Of the potential icing problems, it sounds more likely he was suffering airframe and prop icing and needed the extra power to make up for the drag and deformation of the wing and prop aerofoils. Given that conditions were VMC, that would appear not to be the cause. More probably there could have been some blockage in the fuel supply which would have allowed him to run at higher power but with a very lean mixture and high EGTs, but that would have been nothing to do with icing.