I've seen that kind of thing before (as have we all), where the creationist or the creationist's creationist source had glommed onto some tidbit of an actual fact and then misconstrued it completely, sometimes by mixing it up with something entirely different, and now the creationist you're talking with is completely convinced of that gross misconstrual.
For example, I once got an email from a creationist of high school age who had just been taught in Christian summer camp that the sun loses half its mass every year. My response was to point out several consequences were that to be true and to demonstrate that none of those consequences are found to exist. He ended up realizing that that claim isn't true, plus my searching for some trace of that claim led me to Kent Hovind's infamous solar-mass-loss claim. Now, it is true that the sun loses a lot of mass due to the fusion reaction in its core (about 4.6 million tons per second), though it is miniscule compared to the sun's total mass. It is also true that it is in the sun's core that this fusion reaction, and hence the loss of mass, occurs. It is also true that the sun's core, which accounts for a small part of its volume (either about 1.5% or 15%; I can't remember which), contains half the sun's mass. Somehow, a creationist had gathered those facts and, having no understanding of the science, got it all jumbled up and confused everything together into a claim that the sun loses half its mass every year.
So your creationist heard or read about the earth's atmosphere filtering out some of the sun's radiation (eg, the filtering out of a lot of UV light by the ozone layer) and had misconstrued that to mean that it filters out
all the radiated energy from the sun; more likely than not, he had heard that from another creationist. In either case, he's understanding of science is so meager that he cannot perform the simplest of tests of that claim to find how mind-bogglingly bogus it is.
That the earth is not a closed system is supported not only by the myriad observations of solar energy entering it, but also by the energy leaving it. Here in Southern California we will get our "Santa Ana Winds", strong dry, usually hot, winds which blow in from the desert. During Santa Ana conditions, humidity plummets and the night skies are completely clear. That can make the nights can be much colder than normal through
radiation cooling. During the daytime the earth absorbs heat from the sun and then radiates it off at night. Normally, clouds and moisture in the air will reflect part of that heat back down, or at least trap it kind of like a blanket would. But in the clear-sky Santa Ana conditions, there's nothing to stop or trap that heat radiating out and the night is much colder.
And, yes, all we can see of anything is the light it either emits or is reflected off of it. But my question is what point or claim your creationist was trying to make based on that simple fact.
And I would be tempted to ask, since evolution is just the accumulative results of life doing what life normally does, then if evolution violates the laws of thermodymanics, so would life itself. Which means that the creationist's case is that life cannot possibly exist. I believe we may be able to find a few examples that would contradict that conclusion.