This may be true in the case of an American citizen who violates US law by overtly going to Israel and fighting against terrorists.
However, espionage is completely different. You never know exactly what will be done with the information. In fact (as I learned during an intelligence briefing as a PRIVATE in the National Guard), Russians have been known to pose as Israelis in order to get information out of Americans (i.e., "C'mon, you guys are supposed to help us! We're the good guys!")
The Taiwanese are another such case ... They engage in espionage in order to save money they'd otherwise have to spend buying it from us. Some American kid with info who happened to be sympathetic to the Taiwanese cause might be tempted to give them the info... But the person you're talking to could just as easily be lying to you, in reality having been sent by Beijing.