Basically if the demand for the CPU or GPU is lesser... Then the other can clock up to it's maximum as it has the TDP available.
It cannot maintain both the CPU and GPU at maximum clocks indefinitely, otherwise it's not a "boost mode" at all and Sony shouldn't have even bothered to mention it.
Complete nonsense. Again you didn't listen to what Cerny said. Try again, starting around the 35 minute mark.
The PS5's maximum cpu and gpu clocks are UNKNOWN. The cpu is CAPPED at 3.5GHz. The gpu is CAPPED at 2.23GHz. These are the maximum frequencies allowed that guarantee correct operations inside the cpu and gpu, under all conditions. We have no idea how the cooling system (and power supply) was designed for what power dissipation limit. At worst, it was designed to just hold the 3.5/2.23GHz clocks (with rocket noise or not), at best it was designed to hold 4/2.5GHz clock levels (probably with rocket noise, those are some high frequencies). The proof is in the pudding, and we don't have any yet to eat.
When you place your PS5 into the fridge, it WILL indefinitely run games at the maximum allowed two frequencies as the cooling can handle max power without problems. The ability to shift power from the cpu to the gpu is always there, of course, but it will simply not take place due to the caps.
Now if you are the ranger in the Death Valley ranger station and decide to play a game around noon in the front yard, thing are different, there is a thermometer element hidden somewhere. Then all the frequency shifting takes place (incidentally, Cerny didn't say what happens when you really ARE in Death Valley locations. But so did he "miss to mention" critical stuff in other places). Who wins and who loses depends on what the game is doing at any moment in time, obviously. Don't expect to see significant drops, though. Cerny mentions a 10% in power drop only costs a few % in clock rates, so I'm guessing we won't likely see "bad" clock rates below the 2.1Ghz point on the gpu.