You know exactly what you meant. If you take the poster at face value, he's not a political type but has heard a few things farage has said that have struck a chord. Rather than take the piss and signal your own superiority, just explain that he's probably only aware of the tip of the farage iceberg. That way you might actually change a mind rather than alienate the bloke. This is only one person on here and I'm not blaming you for reform doing well in the polls, but this sort of approach is exactly what got Brexit over the line.