When the Communists were in power they banned everyone else. So what’s their complaint?
Maybe they don’t want to be like them in any way.
However, I'm not sure banning their party will have the desired effect. Political movements, no matter how evil, can become more appealing, more chic, when their are banned. The fact they can claim they are "persecuted" generates sympathy from people who otherwise would not support them.
No, instead of a ban, a madia campaign reminding the citizenry of the attrocities committed by communists would be more effective. Make it a mandatory part of the school curriculum, as early as the third grade. These sorts of things are more likely to work.