If I were interviewing such a candidate, I'd dig into why they built a custom framework. The answer to that question could be quite enlightening, especially if they mention business reasons for doing so, or if they talk about what they've learned since then.
When I started my own business a decade ago, I decided that existing web frameworks wouldn't suit my needs and built my own. Though I built a framework that suited my needs extremely well, it was a massive distraction from my actual business (which wasn't even tech). In interviews, I freely discuss how my NIH syndrome contributed to my inability to get the business off the ground; I've found that it tends to go over rather well with interviewers.
