I, and I think most security researchers do too, believe that it would be incredibly negligent for someone who has discovered a security vulnerability to allow it to go unfixed indefinitely without even disclosing its existence. Certainly, ffmpeg developers do not owe security to their users, but security researchers consider that they have a duty to disclose them, even if they go unfixed (and I think most people would prefer to know an unfixed vulnerability exists than to get hit by a 0-day attack). There's gotta be a point where you disclose a vulnerability, the deadline can never be indefinite, otherwise you're just very likely allowing 0-day attacks to occur (in fact, I would think that if this whole thing never happened and we instead got headlines in a year saying "GOOGLE SAT ON CRITICAL VULNERABILITY INVOLVED IN MASSIVE HACK" people would consider what Google did to be far worse).
To be clear, I do in fact think it would be very much best if Google were to use a few millionths of a percent of their revenue to fund ffmpeg, or at least make patches for vulnerabilities. But regardless of how much you criticize the lack of patches accompanying vulnerability reports, I would find it much worse if Google were to instead not report or disclose the vulnerability at all, even if they did so at the request of developers saying they lacked resources to fix vulnerabilities.