Don't assume that all miners have the same primary costs as yourself, or even most. Mining is literally free if you heat with electric anyway, and it's winter where you are.
Don't assume that I'm mining
If mining is free, then why on earth is a miner who's given it any thought at all on the sidelines? Perhaps, it might be ventured, that some non-monetary cost (the noise made by the mining rigs, one's significant other threatening to leave if mining continues, etc.) pushed the benefit-cost difference negative. Regardless of the reason the hash capacity is on the sidelines, it seems unlikely that a 6% increase in benefit to turning on the rig would lead to large number of those differences turning positive.
What primary costs are there to mining in the general case anyway? Electricity, Equipment, and Bandwidth are all I can think of off the top of my head. Equipment cost shouldn't affect the decision of whether to take capacity offline. Electricity and bandwidth cost should be broadly the same over a given period of real time mining, regardless of the block-solving rate(this is true whether your electricity/bandwidth is free or unbelievably expensive (and if electricity and bandwidth are free, again, why are you on the sidelines?)).