And you will notice that I was actually being generous. The weekly average was based on the 20-year murder-rate average. But the farm murder number you use is based on the total since 1994, rather a lot more than 20 years. The first 2 years of that period includes the highest murder rate in South African history - if I included that then the farm murders go into the 0.0001% range.
What's more -that farm murder number is NOT a count of white farmers who have been killed, it includes every black farm WORKER who has been killed as well (including those killed BY white farmers).
Nobody has a number for 'white farmers killed' -but whatever that number is MUST be lower than the total your "2 per week" is based on.

But anyway you look at it, farm murders are a tiny, tiny blip on our murder stats. Of course they are terrible, but only because ALL murders are terrible. But farm murders are so rare that if they were the ONLY murders, we'd be the safest country on earth.