Putting metal objects inside a microwave, even if they are covered by plastic or other materials, is not recommended due to the potential risks associated with microwaving metal. While covering the metal object with a non-metallic material may reduce the chance of sparking and arcing, it does not guarantee safety.
The reason for the sparking and arcing when microwaving metal is that metal reflects the microwaves, which can lead to concentrated electric currents. These currents can cause the metal to heat up rapidly and potentially lead to sparks and damage to the microwave.
When you microwaved the plastic box of pasta with the spoon inside, it's possible that the plastic box provided some level of insulation or shielding for the spoon, preventing or reducing the sparks. However, this doesn't mean it was entirely safe, as the presence of metal inside a microwave is always a risk.
As for eating the pasta afterward, it's unlikely that you gained any superpowers from the experience. If nothing seemed unusual with the pasta and you did not observe any strange taste or odor, it should be safe to assume that the food was not contaminated by the spoon. However, please exercise caution in the future and avoid microwaving any metal objects, as it can be hazardous and may damage the microwave.