In the grey gas (and cloud) case, subsequent addition
of absorbing substances reduces OLR initially, but OLR must return to the original value at full
equillibrium, so there is a cooling at and near TOA that is temporary.
Again, look more carefully into the Vostok ice core data http://www.realclimate.org/index.php?p=221 - contrary to your presentation
of stable concentrations over thousands
of years, there was no single period in time when concentrations and temperatures were steady stable, they were always changing, and therefore were in dynamics, in a state far from
equillibrium.