That either assumes a spammer makes the effort to program his bot to handle this problem or a bot so intelligent that it can interpret what this "proof you're human" task entails.
The second, I think, can be ignored for now. The first is fairly unlikely, given the current popularity of the site and what a spammer stands to gain (hm, maybe there is quite somewhat to gain. One could register a few million different fake profiles, and use them to find gullible clients for a "I would like to come and visit you, but need money for the trip" scam. Edit: maybe, this whole site is part of such a scam)
Also, if I were to make my bot aware of this "I'm human" test, I also would program in knowledge of the URLs or the pixels of the pictures used, and get a 100% success rate.
The second, I think, can be ignored for now. The first is fairly unlikely, given the current popularity of the site and what a spammer stands to gain (hm, maybe there is quite somewhat to gain. One could register a few million different fake profiles, and use them to find gullible clients for a "I would like to come and visit you, but need money for the trip" scam. Edit: maybe, this whole site is part of such a scam)
Also, if I were to make my bot aware of this "I'm human" test, I also would program in knowledge of the URLs or the pixels of the pictures used, and get a 100% success rate.