I can see where 9001 is coming from with the Piccolo example. His overall chi would be read as 408, but he could produce more chi with charged up blasts, so his overall chi when being absorbed could be bigger than what is read simply as his h2h fighting power. The matter is, will the energy stealing machine gather their chi registered when sensed from a warriors perspective or when read by a machine, or will they take that power multiplied even more so simce they can make their attacks stronger?
By one side, it makes sense they'd take their chi reserves into account when Gohan already filled almost half of Boo's power. Many take the energy needed to revive Boo as tied to the power Boo possess, so since SSJ2 Gohan isn't, like, 40% of Fat Boo's full power (at least not if we consider a 4x SSJ3 multiplier)... then it'd make sense such could be factoring a reserve energy concept. But atill, is the energy needed to revive Boo the same as Boo's power? While a nice theory that makes sense, one could easily argue that Boo needs a certain amount of energy to ba awakened, given all the time he was inactive, which isn't necessarily tied to how much power he can output... just the minimal for him to kick in, and then he can access more as the fight goes on. Maybe the energy needed to revive him could be more closely related to the power he had initially when waking up.
But also, if a power stealing machine would take into account the energy they have dormant, and not simply the read power output, wouldn't Gero benefit way more so from absorbing Tenshinhan? Because his Shin Kikoho is splendidly powerful... yet he gauges suppressed Piccolo as the next biggest source of energy after Vegeta. He also couldn't absorb much of Piccolo's power... Piccolo kept most of his energy unaccessible, so Gero simply couldn't absorb what wasn't there... he absorbed the amount he read from Piccolo.
Besides, I'm not sure they're acessing more energy from their usual level when making attacks stronger... it's like they're, more so, making that energy bigger by focusing it on a single point. They're amplifying what they currently have. It's like the concept of focusing a whole lot of power in a small area... you're increasing pressure, and then the lethality of the power, but not necessarily making its potency higher. The attack will be harder to deal with because it's all focused on a single blast. I think the scouter may be gauging moreso the potential danger of such attack, since, as it was said in the manga, they aren't taking energy from their reserves, they're "making it stronger" by focusing it on a single point. Maybe from a scouter standing point, when the energy is spread out, it's less intense than when it's gathered on a small area, to be read. By that point, if someone absorbed Piccolo, they would get more benefits than by absorbing Raditz?
I think a machine would absorb what their fighting chi is read at... I honestly don't think they are taking from reserves when making chi blasts stronger, since the concept is given moreso as "making it stronger by focusing it on a single point". If they could absorb energy in a way it goes beyond the user's powers, I think Gero would be able to absorb what wasn't on Piccolo's read at power, for instance.