first prequalify it for yourself.. again could be sisal wool... but if if its real sisal... we've been over this before.. you'll have to use a host system..
Ok.. if you get a complete release.. and then permission to knock the sence out of the customer.. you "could" acid rinse with ooper low pressure.. even use a upholstery tool for absolute minimum moisture penetration, and super fast dry... that could remove more soil but possibly still cause browning.. hence the host.. and don't go stingy with the solvent preconditioner.
But if its wool sisal.. relax, and clean the carpet! !dork!