If you actively advertise and give away free food, there is a baseline assumption that you are at least cooking the food in sanitary conditions.

If people get sick after eating the food you gave them, you can’t just shrug and say it was free.

This is doing a lot of heavy lifting, and not really valid as a categorical statement. It's important to narrow the context because "Free software developers" are ultimately still people or organizations that fall into our established systems. There is no specific purchase contract between the provider and user, so unlike commercial software that supply-side obligation is not explicit. There's typically a license that tries to legal-away any responsibility, and this is not so clear-cut. Free software is not found at the side of the road without any providence. It's usually the product of one or more legal entities, promoted, it's use encouraged and maintenance & delivery can be implied by the actions of the developers. All of these things carry varying degrees of obligation within legal, cultural and social frameworks. We try to reduce this down to "no obligations" or "expectation to support for free in perpetuity" but no binary position is accurate.

The last person, I think, most clearly, does "owe" you supply-chain security, in the sense that he bears moral (and ought to be made to bear professional) responsibility for any adverse consequences you may suffer from its lack, though in practice he will probably often protest that he couldn't do anything about it because it's not like he is developer. Whether the developer also owes it is a more interesting question, and I think it greatly depends on what attitude he takes towards the evangelist (does he consider him a nuisance who makes implicit promises the developer is uninterested in delivering, or an ally who raises the dev's profile?).

Long ago, I remember seeing a cartoon which involved a tag-team of two people robbing a third, with A pointing a gun at C and saying "give your money to B", while B comments "I'm really just standing here, but I figure it's best if you do as he says". I'm not sure what exact piece of day-to-day politics this was made to comment on (though it was probably some or another flavour of political violence), but it seems somewhat applicable here as well. The lines just become "accept the supply chain, or suffer my public ridicule" and "I'm just providing the software 'as-is', but you probably should do as he says".

What if you were distributing food, and a farmer who supplied rice to one of the manufacturers of the components of your food grew that rice on a field that was contaminated with arsenic?