Off and on, I've been skeptical of that time since Kreft put it up. It was at the 2017 XC season MMOC meet. That year the meet was at Darby instead of Bradley because of construction at Bradley. The MMOC was previously held at Darby in the early 2000s through to 2010. There was also the Darby Dash that was held there back around the same time. Lately the course has been used as a district site.
If the course is the same now as when Kreft ran his time, then it is probably legitimate. IIRC, the weather conditions on the day of the meet were nearly ideal. Horter was also pushing Kreft and came in at 14:36. Behind Horter was Lucas Bons in 15:13 and at that time Bons was one of the top XC and miler guys in Ohio. Just this past year at Bradley Gableman won his district putting up a 14:55 to Day's 15:05 and at districts last year, Ackley ran 15:04 to beat McMahon by a minute.
The course is flat and fast, the conditions were ideal, Kreft had someone pushing him, and if it is the same course as is currently being run for the district meets, there shouldn't be a reason to doubt it. Also, Kreft was and is one hell of a runner. If he ran at a D1 school at that time I believe that he would have been pushed more and put up faster times overall. Since time really doesn't matter in XC, he did what he needed to do to win based on his competition.
On the 2018 class as a whole, it was ridiculously talented in all of Ohio and the entire country. So many of the guys from that class have had a big impact at the collegiate level.