JBII will not, initially, be selling its diesel for running in an engine. There are plenty of other industrial uses (think boilers and furnaces with fuel atomizers) for their diesel. And because JBII diesel has no sulphur, companies that use it will reduce their air emissions. And the same companies that need it for this use will have plastic waste. They will get JBII diesel for a discount to market prices.
However, the process for lowering sulfur also reduces the lubricity of the fuel, meaning that additives must be put into the fuel to help lubricate engines
my guess is this is why the shift to fuel oil, it is a simpler product, will not have the hassle of engine warranty (oil burners being much simpler and forgiving), etc, etc.....