Define "legally protected views".
Just because you have the right to hold certain views does not mean they are in any way protected by legislation.
My organisation is commissioned to supply a service to a specific demographic, it also presents to the service users in very specific terms. If you came to me offering voluntary service, and you made it known to me that you did not respect or acknowledge a certain aspect inherent to my service users, then I would have no option but to decline your offer of time.
First of all, I am under no obligation to "allow" anyone to volunteer with my organisation. It's entirely at my discretion, and if you don't fit my criterion, then I simply will not ask you for voluntary service. If, against my better judgement, I permit you to interact with my service users, then I have failed in a safeguarding sense because I have assured them in the organisation's constitution that they will only encounter volunteers who are sympathetic, and I can't honestly say I am convinced you can be if you have already told me you fundamentally do not recognise a characteristic of some of my service users.
Ultimately, a complaint would be scrutinised by my commissioners, and if upheld, could well mean the withdrawal of my funding, the closure of the service, and a complete loss of that service to vulnerable people. So no. I'm completely unwilling to take any chances with that, even though I respect your right to hold certain views. The law does not compel me to accept your voluntary time regardless.