If you were to ask me, I'd say the 10-C rating really needs to go after this. It's dogmatic downplay.
I won't deny the SpongeBob characters are small, but it should be common sense that size automatically doesn't equal strength, unless there are no other feats to back up a character. Take
The Knight for instance; he's the size of an insect, yet we don't say "Haha he's 10-C because he's bug-sized". And then there's Kirby...
There's also how a lot of people here argue "haha SpongeBob can't lift up marshmallows so that's a supporting feat for 10-C", even though
lifting strength is completely different from
striking strength.
On another note, scenes like SpongeBob getting overpowered like seagulls (I hate how that's the only scene on that magnitude, yet people think it's consistent) are merely either plot-induced stupidity, or an example of someone upscaling him. After all, are we gonna say Gumball is 10-C now for getting hurt by a balloon,
struggling to lift up a bookshelf, and
failing to bust down a locked door? Or that Daffy Duck is 9-C via
getting harmed by shotgun bullets?