It might make sense as an owner of the startup to outsource your blog. But as a reader I am interested in reading about the experiences of the founder.

If you have little time to blog then write a post in pieces. One post per week is not that much of work. Besides writing a blog will help you in many ways. It will help your organize your thoughts and it will help you gain new potential customers and you will probably make a few friends on the internet as well.