Brexit would not have ruined their business. Being too incompetent to be able to plan ahead and manage risks and opportunities, may have. Of course if one is incapable of achieving such forward planning, then implying one is a good business person really, while finding something or someone to blame one's difficulties on, must be an attractive option.
Maybe they should blame instead the excessive import paperwork demanded by the EU. Or perhaps they could begin to realise that the EU is no friend and no longer a suitable market for them; and explore & export elsewhere. Perhaps check the home market to begin with.