It's a double standard. Men are seen as sexual beast unable to control themselves and if a guy finds himself in a situation like this, this outcome is to be expected of him. Any other outcome would mean he wasn't really a man. Women on the other hand are seen as sexually in control. Both of themselves and of the man or men they are sleeping with. If one ever went on a sexcapades like this, banging two older guys at one time, she would be labeled a slut.
I see no problem with the kid banging his teachers. And it's not just because I'm a guy. One of the main reasons I see no problem with this is because the two women are physically, and hopefully mentally, mature. Meaning if a child were to come from this encounter, and let's hope that doesn't happen, they could properly raise it. If roles were reversed and a teenage girl was knocked up by two guys, she wouldn't be physically or mentally capable to deal with the child, at least properly. And I know this sounds weird, but in a way it was better that he had sex with older women than it would have been if he had sex with girls his age. I'm not saying he's not, and he probably is, but it seems less problematic.