It seems that NOD32 has analyzed this file in past in found first well and then not to be Trojan:
http://www.wilderssecurity.com/showthread.php?t=232326
Without any evidence it is hard to make any conclusion here. I'm not aware how Ultrasurf works and do not have time to test it and gonna deep into but if program use open proxy servers and if there is internal testing and if they are filtered then are terms or site like sex, ****, porn just used to filter out proxies that are set to not works on such a terms.
Such a way works some other proxy programs and testers to get rid of not fully working proxies.
btw
Their chinese site is
http://www.wujie.net/
By their FAQ
http://www.ultrareach.com/usercenter_en.htm
4. Is UltraSurf a Trojan or virus?
A: Neither. UltraSurf provides users with state-of-the-art internet technology to break through firewall safely. It is a popular anti-censorship software, not a Trojan or virus. Some anti-virus software companies classify UltraSurf as a Trojan software simply because UltraSurf is able to break through firewalls. It is a mistake and a wrong classification. We are in the process of resolving this issue with these anti-virus companies through technique channels and legal channels. It is our mission to protect users' privacy when browsing the internet. Please rest assured that UltraSurf will not touch any of the documents on your PC.