I have to agree with the people who say that there should be a FAQ about this. This is an iconic ability of a base class and has been a known issue for 5 years. If there is an easy answer it would take a minute for this whole question to be out to rest. If there isn't an easy answer, well, that's a major fault which should be fixed.
This line is unambiguous and makes it 100% clear that...
I personally read that line as a slightly redundant but possibly necessary clarification that the move-action precludes additional use of the spell effect. I could see someone trying to argue that the 'as if studied for 3 rounds' effect was single target but still getting the regular benefits of the spell against others. Said another way, that line clarifies that they can't have the larger cone effect of the spell active and concentrate on one target within effect while keeping it going.