The no-fly zone is not in question, its justification is. According to OPPD, it was "set up by the FAA as a result of Missouri river flooding" – implying that it had nothing to do with the plant. The articles in Russian refer back to a blog post; the blogger called the plant and got this more detailed info:

Idaho Samizdat: Nuke Notes

I spoke by phone with Mike Jones, a spokesman for the plant. He told me that due to the rising flood waters, a lot of planes and news helicopters were flying over the reactor and some were coming in quite low.

The plant manager told the FAA he was concerned they might collide with power lines or each other. This is the reason the FAA issued a Notice to Airmen banning over-flights of the reactor. The NRC says this isn't a an issue regarding the potential release of radiation.

Here's what the NRC's spokesman said about it

"After last week's Alert, and with all the interest in flooding on the Missouri, news helicopters began flying near the plant. We understand that the plant owner contacted the FAA and asked them to remind pilots of the basic NOTAM is still in effect. As far as we can tell that had zero to do with the plant operations and everything to do with assisting in flood relief."

_{*Lunatic*, n.
One whose delusions are out of fashion.}