he also said
"This is an unexpected move for her, it's too agressive!
Lord Maul, be mindfull, let them make the first move"
So, she did something that was unexpacted, so why not that move?
And it didn't mind for him if it was signed or not, if it wasn't, well... you saw the movie, and if it was, he gave the no-vote so Valorum had to step down, and he because Chancellor, saving Naboo, therefor gaining more power and votes