On a lighter note we have some cases where Tom acted like a fool.
At least Dumbledore said so during the duel at the Ministry.
“It was foolish to come here tonight, Tom,” said Dumbledore calmly.
“The Aurors are on their way —”
Snape had fooled him as well.
“You think he is mistaken? Or that I have somehow hoodwinked him?
Fooled the Dark Lord, the greatest wizard, the most accom- plished
Legilimens the world has ever seen?”
Dumbledore once again pointed out in the cave
These words did nothing to raise Harry’s morale; perhaps Dumbledore
knew it, for he added, “Voldemort’s mistake, Harry, Voldemort’s
mistake. Age is foolish and forgetful when it underestimates youth.
Now, you first this time, and be careful not to touch the water.”
So your claim in the question that Tom is not a fool is not entirely true.
On a serious note Tom didn't construct the opening to the Chamber of Secrets during that year. It was constructed by Slytherin himself (maybe). So it wasn't his choice that the opening was the same room where the trio was brewing their potion.
And, although, there were 2 attacks during the period the trio was brewing the potion in the bathroom. First one was when Harry was in the hospital wing because of losing all the bones in his hand and hence no chance of the trio being present in the bathroom when the chamber was opened. 2nd one was luckily when Harry was visiting library while the other two were playing chess in the common room, so there was no collision.