That's a good point. I feel protecting the peg must be the number 1 priority for Nu, and when a specific threat appears (very cheap NSR, small NBT liquidity creating a highly gamable situation), perhaps it's better to respond. Any response would need to be agreed by Nushare holders, and as I haven't heard any other suggestions of a change / response, that's perhaps unlikely.
I'm just throwing it out there due to a potential risk I currently see.
Right now, if someone had loaded up on cheap NSR, then bought $50k of NuBits, they may cause a pump of NSR price due to buybacks, then dump NSR at a significant profit before dumping NuBits, possibly leaving Nu in a very weak position if only 40% of income from NuBits sales were kept as reserves. The same move would be harder after a period of stable, higher NSR prices and larger market for NuBits.
Whether a measure to halt or reduce buybacks at this time would increase or decrease people's confidence in NSR I don't know - I can only speak personally that I'd be more reassured by accumulating higher reserves from NuBits sales at this time compared to seeing large NSR buybacks.
Question to NSR holders: If reserves exceed equilibrium, would you prefer to see NSR buybacks start as planned, or to increase reserves to a larger degree than planned due to possible threats?