He will not be able to get to a level where his technical expertise matches the coders. However he should (already) be able to listen and understand the business-orientated aspects of the issues put before him. It is probably worth his while becoming conversant with the basic workings, limitations and abilities of the platforms the startup is using, but any more would not be a good use of his time. You might as well require the coders talk accountancy.
For example, he should probably be aware, that no: you can't keep expanding the power of a computer indefinitely. Nor is a cloud solution always the best, cheapest and most reliable. He should probably be told that creating software is (still) basically a hit and miss exercise and that a great programmer does not make a great GUI creator or a great technical designer.
However, he should be brought up to speed on the need for designing in security and that testing, while a large cost in terms of developer time, is an even larger cost if not done. Give him a copy of The Mythical Man Month which should be right up his street.