Response:

Not true. All the material produced at Natanz is low-enriched uranium that is unsuitable for weapons use.  It is under IAEA seal and surveillance.  And it is all fully accounted for.  Any effort to seize or divert this material would be quickly detected and would provoke an international outcry with a very high likelihood of a forceful response, from Israel if not others.

Moreover, converting this low-enriched uranium to weapons-grade form would takes weeks if not months of further enriching, so there would be plenty of time to organize that response.  Under these circumstances, a completely clandestine route would seem far more attractive to Iran than any breakout involving safeguarded facilities.  Stopping enrichment at Natanz will do nothing to address the clandestine risk, and may well increase it by driving enrichment underground. Iran itself seems to realize the risk of using Natanz for a weaons program. That is likely why it constructed the Qom facility.