Would you react in the same way if they were demonetising videos about something you consider fair and legitimate? For example gay rights? The problem here is not whether we consider anti-vax as a legitimate battle, but if we're comfortable in giving a private company the power to decide which opinions should be promoted and which should be silenced.
Please don't equivocate gay rights and anti-vaccination. One is a trait many people are born with that does not harm others; the other is a choice that can and often does harm others.