Hi speed protection (Normal Law) cannot be overridden. The pitch up can be reduced, possably delaying recovery, but not overridden even with full forward stick. If you leave it alone to do its thing the altitude deviation will be no more than 700'. This is why Airbus advise against making pitch up commands during hi speed protection.
Importantly the autopilot disconnects on activation and if you pitch up strongly you can end up in AoA protection. Source Airbus Safety First Magazine.