You're immediately ascribing malice and poor character to these people

Where are you seeing me ascribe malice or poor character? You thinking that having a failure or making a mistake makes someone a failure is projection on your part. I don't view making a mistake as a character flaw.

You overestimate your own ability to resist propaganda along with how much knowledge and information the "average person" has.

I don't even know what to do with this statement. How are you getting to that from what I said? Is it the part where I said the opposite?

I'm honestly taken aback that you're doubling down on "people are uneducated". You have a skewed view of the state of the average person. 5% of people work multiple jobs. You're condescending to view the average person as poorer, less educated and less able to become educated than they are.

People don't like being talked down to. Yes, I think if you become an antivaxer you've made a mistake. That's not a judgement on them, but on their beliefs. It has nothing to do with listening to them or how I might address their concerns. You're the one whose not really understanding people, because the people you're "understanding" are a caricature of what you believe antivax people to be like.
No, I don't think someone with two jobs working paycheck to paycheck and still underwater has time to research them. I don't think the level of knowledge I shared above (vaccines teach your immune system) requires that. I also don't think that most antivaxxers are in that position, and certainly the average person isn't.

How do you expect to reach anyone if you won't make even the slightest bit of effort to understand them?

What makes you think I think that? Do you think empathy precludes acknowledging a mistake? Or the other way around? I honestly don't understand the mindset you've expressed. Addressing mistakes is the heart of teaching someone. It's not an attack, or a value judgement, and it's not incompatible with understanding why the mistake was made. That understanding actually helps quite a bit.

You need to step back and think about why you perceive someone being described as making an error or having a failure of reasoning as a value judgement.

The entire premise of that article is how to effectively guide people towards getting vaccinated. The only reason you would do that would be if you thought it was a mistake to not get vaccinated.

Also...

It’s wrong to assume that people are ignorant, irrational or have naively swallowed online misinformation.

I agree with the article, and also that point. You don't need to talk down to the person expressing the concern. They have just as much agency and information access as we do. Everyone makes mistakes or gets something wrong.

It's not your job to teach them.They're the ones that failed, so they need to "do better" and that's it. You're a good person. You didn't fail in critical thinking and tumble down the alt-right rabbit hole. You want to hold everyone else to a higher standard because it absolves you of responsibility. Bad things happen because other people failed. It's not your fault.

That's a lot to unpack. What responsibilities do you think I'm trying to be absolved of? You seem to be implying that it's my job or responsibility to teach people about vaccines. I try when it comes up to advocate for them, but I'm not actually a public health professional, like I said before. My knowledge on the subject is superficially better at best. It's no more my job to teach them than it is theirs to teach me.
I'm not even sure what you're getting at with the "bad things", and "it's not my fault" part. That's a lot more mysterious backstory than I actually have.