Predatory Journal edit

I received an automatic warning that this article cites a WIT open access paper, and WIT is considered predatory and thus unreliable due to lack of peer review. The cited article is written by JR East employees and I would therefor consider it a primary source, which does not need peer review.

Is this an appropriate source for this article, especially considering that its content is also confirmed by other references? Or should I just get rid of it and use another reference?