Sorry, but this is a really bad solution to a non-existent problem, but fortunately this isn't anything that's even practically possible to get implemented by SE for our little site anyway.
First of all, as explained in the answers to this related question spoilers don't actually have a shelf-life on this site, nor are we able to even define one. What is a spoiler today is one next year too and we don't ever want to have people spoiled by a question title. "You had time to watch the film" isn't really a good excuse then.
Apart from that, what you propose is even worse than nonsense titles like "what did he do in this scene", it is no title at all. How is this remotely any more sensible than even the most general of crappy titles? We wouldn't want to have useless non-titles for half a year, hell, not even for a week, especially when those questions concern hot movies of public interest. People already have difficulties finding questions and not asking duplicates for the newest MCU blockbuster. Stripping questions of their titles would make this an absolute nightmare. Saying "but it'll be fixed next year" is a terrible consolation if you could as well have proper titles instead.
I got a better solution to your problem, one you can even apply right now rather than making it someone else's problem half a year later. Basically, write sensible spoiler-free titles! Really, if you literally want to write "what did he do in that scene?", I'm afraid you're...doing it wrong. I have strong doubts this is really the only grammatical construction you're able to come up with that properly summarizes your question. Rather than throwing your hands in the air and saying "eh, guess someone's gonna figure it out in a year", maybe think a minute longer and I'm sure you'll find a good title.
And if not, fortunately the community is able to help you and edit your title for you, that's the joy of collaborative edits. Hell, even actually writing "what did he do in that scene?" and having someone else fix it today for you is better than what you propose. Even the worst titles are better than surrendering to spoiler paranoia and just entirely giving up on question titles. Because they can get fixed and they will get fixed, since there is a motivation for proper titles. But that motivation is void when we just surrender to live with non-existing titles for months and with blatant spoilers after that.