Why did Splinter not show the canister until TMNTII?

[Original TMNT Cartoon Fan]

Originally Posted by saul

He says basically: "You have not seen this until now..."

So, why exactly would he feel compelled to hide the canister from the turtles all this time? Especially since it wasn't a secret that the ooze came from a broken canister. Wouldn't the turtles want to see what was on the can?

Why are they always saying the ooze in the films? In the 1987 cartoon, it's "mutagen". And why is April working for Channel 3 instead of Channel 6?