If there was a "flaw" that you could exploit to beat the game without doing nothing, that would not be cheating? I disagree completely, the game was clearly not made to be that way. In a way exploits are still cheating.
In my opinion ANYTHING that makes you easier to control during Seija's attacks are cheating, like changing your monitor settings, rotating your monitor, rotating your head, changing your controls, Alt-tabbing to fix the screen, even pausing for no reason is unfair (and ZUN seems to agree, "please do not pause the game for any other reason than to stop playing"). Abusing MarisaB's power 3 in MoF is cheating as well.