Should the government ban its citizens from using cross-border payment methods (like crypto) to send money to relatives in OFAC sanctioned countries (Palestine, Iran, Cuba, Venezuela, Russia, and North Korea)?

No, but funds must be monitored, controlled and regulated to prevent financial support to hostile regimes, to ensure compliance with international sanctions and national security policies

No, but these methods must be strictly regulated by the Australian Federal Government in order to prevent terrorism.

Depdending on what country that may be sanctioned like Russia may be fine but others may not be allowed

There should be regulations in place that would have citizens that use cyrptocurrency declare their intended purpose with it, or if they move a certain bracket of crypto in a certain amount of time. I'm not qualified to speak too much on Crypto.

Not all of the citizens of these countries are terrorists or criminals. As long as the government and security agencies are aware of it, then I have no problem

A ban would do nothing to stop the money going to terror organizations, they would still get the money through to them some how.

That's a tricky one to answer. I think it probably requires regulation. How a person chooses to use / spend their OWN money is their own business, and if they have relatives in said countries and crypto is the only method they have of getting money to them, they should not be prevented. At the same time, bad-faith actors in that space should not be able to funnel Australian money to corrupt, antagonistic, adversarial and/or despotic regimes and terror organisations, that could be used to violate human-rights and/or be used against our own nation's interests.