Citation needed.
What that guy said makes zero sense, because that's not how emulation works, in the of the day what really matters is how much code translation it'll need to be done and how many components developers will need to reverse engineer, so using n64 and gamecube as examples make zero sense, n64 is a MIPS console for Christ's sake.
Same for your arguments, it's kinda hard to say the gamecube is more powerfull than a 3ds, let's review the CPU: for the gamecube the cpu is a single core PPC clocked around 400Mhz, the old 3ds CPU is ARM 11 clocked around 280MHz, but the 3ds is dual core. For the new 3ds the cpu is just faster, I think it clocks around 800Mhz but I'm not sure it's single core.
Depending on what you're going to run, on real hardware, the 3ds might be faster or the gamecube might be, specially because the thermals inside a gamecube is better, but I think a gamecube is no match for a New 3ds. For emulation? On a switch you'll probably have to translate more code coming from a PPC CPU than an ARM11, so you'll probably have a harder time emulating gamecube than, let's say, a New 3DS even tho a New 3DS is way more powerfull. OFC that's only for CPU, there's GPU, audio etc.
Unfortunately emulation is not as simple as non-coders paint it to be, too many variables, that's why a console as ancient as a n64 is still kinda hard to emulate nowadays.
