Charities rely on building bonds and relationships with the public to drive awareness, fundraising and sharing of their stories and successes - bonds which are forged in empathy and humanity. People don't want to be bullied into supporting causes, (and, arguably, such 'support' would be disingenuous and short-lived at best).
The truth is our right to choose is widely curtailed for very good reasons. We're not free to drive as fast as we choose, or in what direction we choose, or to smoke wherever we choose. The reason is the public good, to protect the vulnerable. It's simply untrue that suicide affects no one else. Nor is it true that assisted dying is a purely personal matter.