They already had a uranium enriched to 60% according to the IAEA. https://www.iaea.org/newscenter/pressreleases/update-on-developments-in-iran
Sure starting from nothing to enriching uranium to the level needed to build a nuclear weapon would take a long time. But a country that has a uranium enrichment program that has already enriched uranium to 60%?
Also, random people holding kill trump banners isn’t the same as the Iranian government making a feasible plan to assassinate the president.
The IRGC controls information in Iran. Large banners that say "We will kill Trump" wouldn't be put up if the IRGC didn't approve. Also they've wanted kill Trump since he assassinated Soleimani. Killing the Ayatollah probably didn't change that.
I'm not saying Trump or Netanyahu are good, or that Iran doesn't have a reason to want to kill them. But let's not pretend the IRGC are innocent little lambs that would never ever do anything wrong. Trump, Netanyahu, the Ayatollah, the IRGC are all a bunch of shitbags.