In reality, the fact that the price of Bitcoin is rising is the best time to do so. Since the value in fiat is high, turning off machines does not significantly affect the operation, as the money earned from mining continues to support costs and make a profit.
Well, yes, that's a valid point. However, my argument is, if the profit is high, I'd rather harvest it now. The percentage increase in net profit outweighs the block fee. I'm not saying my point makes more sense than yours, but you need to keep in mind that if Foundry turns off gears to achieve anything (be it higher transaction fees or lower difficulty), they would only benefit from 25% of the goal they set, whereas anything they lose is 100% theirs.
If the above is not clear, let's put it into actual figures. If Foundry underclocks all of its gears by 10%, the effect on difficulty would be a drop of 2.5%, and the transaction fees would only go up by 2.5% (since there would be 2.5% fewer blocks for roughly 2 weeks).
Out of this 2.5% increase, Foundry gets only 22.5%. So if the total fees are 2016 BTC per epoch, they now become 2,066.4. That's an extra 50.4 BTC, of which Foundry would get 11.34 BTC. But they have lost 10% of their cut out of those 14,616 BTC. So instead of making 3,654 (if they kept their 25% share), they would make 3,288. That's a loss of 365.4 BTC in a single epoch.
In the next epoch after that 2.5% difficulty drop, they would make 2.5% more profit. So instead of 3,654, they would make 3,745.35 BTC or 91.35 BTC.
So they are up 91.35 + 11.4 = 102.75 BTC, down 365.4 BTC, net = a loss of 262 BTC.
Obviously, operating at a 10% underclock means more efficiency, and thus their power bill would be lower than just 10%, so maybe we can reduce the loss by 10-20% or even 30%. They are still in a net loss.
Again, another reason I say it would make sense to do that in a bear market where gear efficiency matters most. When net profit is close to zero, gear efficiency matters the most. When net profit is high, you are better off overclocking than underclocking. It's just how I would act if I were them. It's how I conduct my mining business as a small-sized miner.