I think the reality in most situations is this: criminals and especially stock thieves are an ongoing and permanent threat. They operate seven days a week, occasionally by day, but mostly at night.
Bikers are not always around, mostly on weekends and in more remote areas even less regular. During hot summer months, bikers get scarce and very, very few bikers ride around at night. So, a biker, or bikers are the least of any criminal’s worries and will not pose much of a threat to them.
Locked gates is indeed a PIA, but they certainly do help prevent crime, especially on remote roads where criminals have to get to and from there objective by vehicle. The gates around Colesberg all have cameras, which automatically takes highly detailed pictures of the vehicle and inhabitants, when they stop at the gate. If I was a criminal, I would sure choose one of the roads without gates and cameras to do my thing.
That said, any road user must have a means to pass through a gate, immediately and that responsibility rests squarely on the the gate owner/s.