It would make sense to observe an increase in troposheric temperature followed by an increase in height/mass and say that the latter was a reaction to the former. However, there is quite definitely no such observation.
If there was no warming of the troposphere, there would be no change in the height of the tropopause. Analyses of Microwave Sounding Unit (MSU) data to derive tropospheric temperatures have heretofore not shown an increasing tropospheric temperature trend. However, that picture is changing, according to abstracts of papers from two different groups that will be presented at the February American Meteorological Society meeting. These analyses, which include one by the Marshall Space Flight Center/University of Huntsville group that performed prior widely-quoted MSU tropospheric temperature analyses, DO show a warming of the troposphere. The increase in tropopause height is consistent with these analyses.
The implication that the authors of the study under discussion may have wished to avoid was that the prior analyses of tropospheric temperature were in error. I guess he'll wait for the researchers themselves to provide the update at the AMS meeting in February.