It is not about stopping supporters; it is about sending a message. Canada is basically saying they could do whatever they want, even go as further as blocking the right to get the money, there could be methods to get over this of course but that doesn't change a thing. Don't get me wrong, after seeing millions upon millions of people die from covid and a horrible few years period, I would prefer if these truckers get a vaccination, that would be better and I hardly disagree with them on their stance.
However, even if I disagree with them, I would not take their freedom away when it is about finances, their "freedom" to not get vaccinated could get people killed, but their freedom to get money wouldn't, it would hurt nobody at all.
It is not really about "freedom" in this case, it is about people doing something that is illegal. The fact that you would confiscate all the possession of someone who is doing something illegal existed since time has started.
If someone commits a crime, they pay for it. This isn't always jail, it could be picking litter up the road, it could be paying a fine, if you go through red light you pay a fee for it and that is basically the situation here as well. It is not about a punishment, it is about do not support people who are doing something illegal.
I know that it is not "exactly the same" but let's assume there is a group who kills people, a terrorist organization, and people sent money, wouldn't you want government to stop that? I know I would. This is the same thing, there are people who are committing a crime and getting financial help for committing that crime is not alright, even though it is a tiny crime according to many.