Currently, redirect timing allow check is determined by whether there is cross-origin redirect, whether cross-origin redirects have opted-in, and whether final response passes timing allow check. The problem is that these three factors can't be computed until loading has finished. Whereas, we want to expose NT2 instance as early as possible, which means NT2 instance can be available before main document has finished loading. But leaving this redirect allow checking non-deterministic also seems buggy.