Become a Party Member and you lose your freedom?

Referring to Zaid's being sacked report, I really wonder wouldn't it be better to remain free from political party membership where one can still continue to practice the freedom of going to places without being questioned or sacked or branded as traitor. I wonder if there were any proof that he was there to betray his party? Maybe he went there for the free food and drinks, or maybe he went there to disturb the opposition event, or maybe he went there to meet a relative or old friend? or maybe he was there to recruit new members and trying to get oppositions members to defect over to UMNO? Is there such a rule in every political party that one cannot be seen with or at oppositions functions etc? or is it just UMNO? Zaid probably have to accept his sack if UMNO does have such rules, afterall rules are rules and he has broken that rule. But I think this rule is bad for UMNO's image because it can easily be interpreted by others as oppressive. UMNO should consider abolishing this rule in the party.