> In fact, if you don't know about biology or virology, the "I don't know if vaccines are safe" is a totally reasonable stance to have
That's not really a stance, that's just a statement of fact. The problem comes when people assume that this statement of fact about their knowledge imparts any information about vaccine safety.
I'm broadly of the opinion that someone who "do[es]n't know about biology or virology" should:
A) keep their opinions on biology and virology to themselves, and
B) listen to the people who do know what they're talking about when their decisions will affect others.
It's all fine and well to make decisions based exclusively on your incomplete personal understanding when it only affects you, but that's not the case with vaccination.
> and not getting a vaccine is also a reasonable decision if you're not sure about the safety.
Imagine you're standing at the edge of a river. There's a bridge to cross the river, but it looks a little rickety and you're not too sure it's safe. Alternatively, you could try to swim across the river.
Now imagine that you've just seen 3.75 million people get eaten by sharks trying to swim across the river, and there's a team of architects who have inspected the bridge telling you that it's safe to cross.
I would not describe anyone who tries to swim as behaving reasonably.
NB: throughout this comment "you" is used as a generic third-party pronoun to describe any individual, not you personally.