Some more points to consider ...
Firstly...all species of theraphosids in Africa, and even for that matter, African islands, are called baboon spiders, not only those found in South Africa.
Secondly...The collected "Pterinochilus" spp. in South Africa (which would be the "Golden brown baboon spider") is now called Augacephalus junodi, not Pterinochilus.
There are Pterinochilus spp. found in South Africa, but thats a topic for another day.
The fact that Pterinochilus is found in South Africa, poses a very real threat that an exotic species of Pterinochilus, like murinus, would not only stand a chance of destroying other less aggressive local genera, but could also hybridise with local spp. of Pterinochilus, which could be disastrous.
It has been proven in Europe that Ceratogyrus spp. can and do hybridise, so the chances are good that Pterinochilus will as well...
Thirdly...Genera like Heteroscodra, Stromatopelma, Hysterocrates, Pelinobius, Encyocratella, Monocentropus etc. are also called "baboon spiders", but they are not represented by any species in South Africa, so are therefore not considered a threat to local species.
More than likely, if they were a threat, they would have walked accross the borders millenia ago, and colonised areas in South Africa...remember, boundaries are man made, not animal made