Yeah, I will qualify that remark. Risk is very very low.
Generally when you talk about getting HIV from oral sex, the risk is to the person who gives oral sex to a man. Precum can contain HIV, although the saliva has enzymes that rapidly deactivate it. Ejaculate (i.e. semen/cum) can be loaded with HIV in a person who has a high viral load (due to untreated HIV), and if there are cuts in the mouth, transmission is actually quite likely. All the factors need to be in place though.
Receiving oral sex as a man is very low risk. However, if SP is HIV-infected and has a high viral load, and she has blood in her mouth for any reason, transmission is much more likely. So for example, if teeth were just flossed, or there was a visit to the dentist, or there is significant gum disease, etc. Then blood could be present which, in this scenario, would be teeming with HIV, which could enter your body through your urethra, urethral meatus, or through small breaks in the skin of your foreskin/shaft or the mucosa of your foreskin/glans. Again, risk of this happening is very low but there are cases. If you have lesions on your penis from herpes, or even breaks due to trauma from sexual intercourse this is also a factor.
For oral sex on a woman (giving or receiving) it is basically nil.
About HIV and Oral Sex:
http://www.cdc.gov/hiv/resources/factsheets/pdf/oralsex.pdf