Thank you for the report and apologies for the delayed reply.
I don't know why google.co.za works differently than other multi-level TLDs. I suggest adding a "user include" on the Tampermonkey dashboard as a workaround.
Open the dashboard, click the script name, then click the Settings tab. You will see a box listing the standard included domains and below that, an empty box labeled "User includes". Click the "Add..." button below that box and paste:
and Okay that. Then reload your search results page and the block buttons should appear.
Doesn't seem to be working on google.co.za through Tampermonkey. Does work with Greasemonkey.