There have been cases of large fans started with N1 frozen (ice in the LPT, thermal lockup, etc.) and no harm done if it's only a short period, not above idle.
One potential concern is lack of seal pressurizing air drawn from a fan/LPC stage, thus possible oil loss; so such operation should not exceed OEM limits (possibly 30 seconds or so).
Please enlighten us as to the OEM limits for the abnormal start you are referring to.
If I had such a start I would be extremely concerned and abort the start well before idle.
This is a windup surely.