What Mr. Van Loan was probably referring to is just the normal administrative process of applying for a grant, and the review process, and the certification that comes with this, whereas a tax credit is automatic. If you meet the criteria, you apply and you will receive the benefits of the tax credit. With a grant program, again there's investment up front in terms of applying. When resources are limited, you may or may not be the recipient of a grant in the end. To some, it could be a disincentive to applying, and there's also a certain time frame around the administration of a grant.
On October 17th, 2017. See this statement in context.