@AStoyanov Don’t know a great deal about SalesForce or SalesLoft, but as an alternative suggestion.
Can you syncronise lists between the systems? If you can, you could create an exclusion list in Hubspot and a corresponding list in the other systems.
Then you can eather bulk assign contacts to ‘Static’ lists or use filters to add contacts to an ‘Active’ list (eg all contacts who are opted out of x,y,z)
Could you then us thease lists to update workflows on the saleforce side, or exclude the contacts when sending emails?
Just a thought