Exactly. StatorVane think of it like this:
Engine is Max rated to ISA+15.
If the temperature is COLDER than this, the engine thinks - I'd better spin a bit slower, because if I spin at 100% with this cold temperature, I will produce so much thrust I may break something!
If the temperature is HOTTER than this, the engine thinks - I'd better spin a bit slower, because if I spin at 100% sucking in this hot air, by the time it is compressed & fuel is added it will be SO hot I will damage the turbines in the hot section! I know this will result in reduced thrust at these temps, but the pilots know that as well, and take the reduced thrust I am providing into their calculations.
If we use REDUCED THRUST we tell the engine it is really hot, so the engine spins slower, thinking it is protecting it's innards (when it is actually just providing a larger buffer before the limit, reducing wear & tear). We know that the engine is providing less thrust - and use the appropriate temperature table to take that into account. (Incidentally, we use the table for the thrust provided at that hot temperature, with the engine spinning a bit slower, however because the engine is taking in denser (colder) air than the table assumes we actually get a little bit of "free" extra thrust.)