Snail takes a 1.3 days to crawl a mile, 280 miles a year. With a huge amount of wealth you can just move to the otherside of the country or ocean every 6 or 7 years.

I can't permanently trap it, so I can put it in a safe that opens after like 1000 years?

Sort of. It’s just “it is also as intelligent as you are, immortal, and does everything in its power to reach you. If it touches you, you die.”

Ironically, letting it out of your sight is the worst thing you can do. Because once you lose sight of it, you’ll think you’re safe… Until some random Tuesday night at 3AM, it crawls into your bed and kills you in your sleep. You don’t want to just turn tail and run. You want to keep an eye on it, so you know where it is at all times. Pay a friend (or even two friends) to collect it in a secure container like a fireproof (airtight) safe, and watch it while you sleep.

Next, you want to start working on a more secure container. After all, you’re in it for the long haul. You want something that won’t corrode over time, has no easy openings, and will be difficult for someone to (either accidentally or intentionally) crack open. Concrete is a decent choice for a core, just for its massive compressive strength. It won’t easily crush. But it WILL degrade over time, so you’ll need something else to protect it. Tungsten would be a good choice, but it’s expensive. So maybe keep the snail encased in concrete, (checking it every few days to ensure it’s still structurally sound) while you wait a few centuries for your wealth to grow. After all, you have time.

Once you have enough money, encase that shit in tungsten. You want this shit to be impermeable and permanent, so don’t skimp. At that point, you can probably let your guard down a little bit. Only check on it every year or two, at most. Maybe keep it in an empty room with quadruple motion sensor alarms, to detect if the snail manages to escape. After all, this is the future and I’m sure the tech exists (if the rest of the humans haven’t bombed themselves into oblivion yet.)

We could go farther, and assume humans are spacefaring at this point. Do you consider trying to launch it into the sun? Into a black hole? You could simply yeet it as far away from yourself as possible. But then you’re getting rid of the only thing that can actually kill you, which you may end up regretting eventually. After all, if you’re the only thing left after the heat death of the universe, you’ll probably be wishing you had kept that snail a little closer to home.

Decoy snails too

Enough wealth to send a snail to space?