Where are you getting the idea that it's the only thing that can? Either way it is speculation and guess work, there has to be a reason they didn't actually show any Rolo stabban.
And considering this is Code Gayass retarded shit happens left and right.
"Oh no his mech is too amazing, we're doomed"
BAM SMOKE/EXPLOSION OUT OF NOWHERE
"Look at my shiny awesome new mech that kills all other mechs with a powerlevel less than 9000"