I think you got lucky the first time. Traditional political candidate campaigns and mainstream parties are supposed to comply with some FEC regs about respecting unsub replies (I think it's tied to getting broad access lists and maybe reduced rates for campaigns), however a LOT of texts and robo-calls (whether supporting candidates or initiatives) are now funded by PACs who seem to have no issue using spammer SIM farms and AFAIC are under no regs.

Since there's no way to tell PAC texts from actual candidate-funded texts, and the PACs seem to now be the vast majority, I always hit the checkbox to block and report as SPAM to my telco. Not that it'll help much but if it's an actual candidate, the telcos whitelist them anyway (because of course politicians passed a law that requires them to), and if it's a PAC maybe it'll burn their SIM farm number pool a little faster, costing them more.

If you're on Android, I highly recommend: https://github.com/aj3423/SpamBlocker. The UX is a little obtuse to set up the first time (ask your LLM) but once set up it works great.