it would reach "close to100" even under normal conditions if you stopped the engine after high load

no circulation = no heat dissipitation. Starting the engine from that hot temp and the temperature will immediately (almost) drop back to 90 ish. Same for idling actually so no big issue there as far as I can see.

Japanese vehicles have setup the temp gauge so that the needle stays in the same spot from 70ish C to 97C.....if you see it move you are pretty screwed already on a Japanese car. It would stay in the middle and rise up to the redline in absolutely no time at all.

good luck.