If we agree that the average Joe won't bother using an open-source wallet, when all the ads and Google searches point them towards a closed-sourced one, I don't see them doing any research about who the original creators of the code were. A very small number of people will care about that information.
That doesn't mean it isn't worthwhile pursuing. The average person does not care about privacy - that does not mean we should abandon privacy tools. Hell, the average person does not care about bitcoin, and is happy just to live in their little mass surveillance bubble, using their government controlled currency which can be censored or seized at any time.
And again, there are plenty of examples of thriving open source projects throughout the bitcoin ecosystem as well as throughout tech in general. The assertion that if you make an open source product it will immediately be cloned and you will put out of business is demonstrably false.