Good catch, it is just the minimum (so equal to or greater than)
The previous version of rules had bullet points that said Jack = 2 or more Items, Queen = 3 or more Items, and King = 4 or more Items. When I condensed that into one bullet point, I forgot to add "or greater than" to the main rule above that bullet point. It has now been fixed to properly say, "To attack a Knowble, you must play a number of Items from your Arsenal equal to or greater than its Toughness."