Mass slows things down, not emitting radiation. It puts a lag on warming and cooling, net effect on the average temperature (with a constant mass) is zero.
The greenhouse effect posted by evil and described by the ipcc is not about slowing down the transfer of heat, but about heat being derived from energy sent back down by emitted radiation by co2 in the atmosphere. I've stated many times that that theory violates the laws. I've asked you multiple times to post your version of the greenhouse effect,.
The notion that heat takes longer to leave is folly. If it takes longer to leave, then it also must take longer to arrive. Net result, zero. But that is not what the theory describes. As with any heat transfer system, if the input is increased the output will increase also over time.
The Stefan-Boltzmann equation is a mathematical calculation model, not a description of what is taking place in real life. Any physicist will tell you that you cannot use it when and where you want and derive conclusions from it. Same reason the ether model is still a helpful tool. Therefore reducing real life objects to black bodies is helpful for calculations, but it can only be used for an outcome not for a behavior.
The environment the object is in is indeed a key factor, but not the emitted radiation should be considered, but the energy levels of the objects. A high energy object will emit short wave radiation and a colder object will emit longer wave radiation. A high energy object will not absorb the long wave radiation, as it is emitting much shorter wave by itself. In order to calculate how much radiation is absorbed one has to deduct the field the object is in, from it's own radiation. But again, this is not proof that it will get absorbed. It will just emit less.
I'll try and dig up more information about absorption and emission of radiation.