When the story first reared up, my reaction was 'this is legal - even though I do not actively support the death penalty, so let the company go about its business unmolested', and my reaction is unchanged, but I have been doing some digging to see where else business could get itself into trouble
When thinking about the death penalty in the US, I imagine that a lot of us think about the electric chair and -
"places in the world which still reserve the electric chair as an option for execution are the U.S. states of Alabama, Florida, South Carolina, Kentucky, Tennessee and Virginia. (Oklahoma, Arkansas and Illinois laws provide for its use should lethal injection ever be held to be unconstitutional.)" SourceAnd British-owned energy companies are active in the US electricity market, including National Grid and BP.
The state of Utah has been known to employ death by firing squad. Idaho and Oklahoma have it as a secondary method. Source. As readers may well be aware, the UK has a lively armaments industry.
Both firing squad and electrocution can be considered as current mathods in that they were applied last year. Lethal gas and hanging have not been used since the 1990s, although one might note that we have a chemical industry, and probably engage in rope making too.