No, they meant democracy. You are conflating the terms "ruler" and "head of state" if you think their comment is about monarchy vs republic. It's not as if no president has ever been assassinated either: people kill for power, not so much for ceremonial titles.
Going a bit on a tangent here, but it is for that reason that I personally prefer the European monarchies over the directly-elected presidencies of e.g. France and the USA: it's very hard to have a meaningful pluriform democratic society when national elections break down into a single-winner-takes-all outcome. I much prefer the democratic structures of e.g. The Netherlands, Belgium and Germany, where the election outcomes (and, importantly, the media narrative surrounding the elections) are focused on the composition of the legislature, and the subsequent ruler is determined by negotiations between the winning political parties.
Of course, Germany is a good example of how to run a republic and still have a pluriform democracy, and the UK is a good example of how even a constitutional democracy can devolve into winner-takes-all outcomes (namely, by allowing a few large parties to monopolize the entire political landscape). But in general, I'd say that the countries that do not directly elect their head of state are much healthier democracies than the ones that do.
(yes, I'm aware that most countries that elect their head of state also have separate elections for their legislative bodies. But going by the media coverage of US presidential elections and the recent re-election of Macron in France, that seems an afterthought compared to the democratic processes in more representational democracies).