There's a bit of apples to oranges comparison going on here between open hardware and open source software with regard to liability. The situation here is falling into the same trap that the RIAA/MPAA/Copyright institutes fall into when trying to compare piracy against theft of goods.

Open source software is usually provided free of charge and at the cost of 'time' by the developer. It's also often produced by the developer as part of every-day problem solving for something else, in which that something else is often a paid gig (i.e. releasing a generalized library that was used to solve a problem for an application that has paying users or for a customer's bespoke development effort), so even in that scenario it can be seen as being produced at no charge. Once 'produced', the product can create unlimited numbers of itself at zero cost.

Open source hardware comes in a few pieces: (1) The specification, which can be completely open and released without promise of warranty against defects and which comes with that transparency, (2) the actual hardware product, which is paid for by the customer, often at a profit but not required to be and (3) the software behind the hardware (bootloaders and such) which should also be free. There are costs involved in hardware production and purchase that do not exist in the software world[0]

Of these things, most consumers would expect the second to come with a warranty of some kind against defects and it would be an intelligent thing for a company -- even one operating as a non-profit -- to mark up the product enough to offer a suitable and clear warranty. In the case of Intel, a very for-profit entity who keeps its specification, documentation, and flaws under lock and key for the protection of its business and, quite rightly so, aims to sell its product in a manner that maximises profits for its shareholders, all consumers expect a product that is going to be warranty protected.

Where this gets tricky is explaining Spectre/Meltdown to the average non-technical person[1]. It's reasonable that Intel couldn't have noticed this flaw even if they were believed to be employing every possible method to ensure the protection and safety of their customers[2]. The complexities around this issue are very high and the company can reasonably be forgiven for missing the problem. But most consumers won't understand this -- what they will understand is that shortly after receiving the mitigation against the flaw, their shiny new processor got a whole lot slower, or their PC stopped booting. They'll blame Microsoft who will in-turn point the finger at Intel, and they'll join whatever class-action lawsuit fits most appropriately for them.

Personally, I don't see how they avoid a large recall effort similar to the one that happened with early Pentium models in the 90s where they had a flaw that led to calculations being incorrect -- a flaw that could be corrected in software, as well, but that was clearly a hardware flaw.

Will the same thing happen to an open-source chip with a hardware flaw? Probably, yes. Will it be targetted at the company that produces the chip or the group that produces the specification? If the two are not one-in-the-same, it'll probably be the responsibility of the chip producer to handle the warranty claims and might result in a hardware recall of sorts unless the issue is one of software running on the chip that can be patched. The difference is that open hardware might spot the problem before production, and even -- if not -- the problem will have many more eyes on it for providing solutions.

[0] See paragraph 1. I'm not saying software production is free of costs; but unlike hardware production, it's possible for software production to be completely free of costs.

[1] Hell, it's difficult explaining it to industry insiders.

[2] Something which, given the debacle around the Intel ME, is very debatable.