Assalamu alaikum Ustadh. I was told by a brother, who claims to be a salafi, saying that his sheikh said it is permissible for us to use cuss words because it is not in the Arabic language so the cuss words does not hold any weight. This seems very strange to me.Is there any truth to this?

Ustadh AbdulAziz al-Haqqan

Never, and I highly doubt if not positive that there is no sheikh that would ever make such a claim.