I just thought of another reason for using Al this way.
Since the heat is being transferred to air, which would be much slower than the 2, using larger fins with lesser thermal conductivity might be more desirable than smaller fins with higher conductivity.
This would also be accompanied with other design changes like greater fin-fin gap, which is better for use with lower pressure fans.
So overall cheaper design and lesser noise.

Of course one could still use Copper fins with the same design for marginal performance increase, at the cost of more weight.

The problems and complications with your method:

1. Suppose Cu is much faster at heat transfer and you only briefly touched it. Your skin does not actually sense temperature, but rate of heat transfer, which depends not only upon the material temperature but also upon how well it will transfer heat. Better use a thermometer.
2. As explained in https://lemmy.nz/comment/20463232, you need to make sure both have been given the same amount of thermal energy and not just heated upto the same temperature. The best way to do so, is by embedding a heat generator right in the middle of the block and transferring a measured amount of energy. e.g. You can embed an electric heater wire (you will require insulation too. That's your headache (ceramic, perhaps)) and pass current using a power source that gives a measurement of the total energy.

One of the main reasons for Copper to have seen a higher variety of use cases is because it is monetarily cheaper, so is preferable even in cases it might be inferior to Silver.

Yeah, but won't it also be much cheaper than machined, branded stuff?

Honestly, I too had similar thoughts ~ a decade ago.
But then I looked back at my childhood, realised how much of a fool I was and how many times I was manipulated and understood how that could have worked in this context.

While I hate dogs, I can't really condone this.

That would be, "100% and I can bet $100 on it.".

Let's hope his neighbour is not on Reddit.

On the other hand, the guy upstairs me hasn't fixed their seepage problems in years and my ceiling is watering. Maybe no HOA here.

What's the chance that the US govt. is deliberately fabricating mails with anyone who had hinted having talked to Epstein?

https://iknowwhatyoudownload.com/

Ahh right.
Perhaps he didn't consider the kinds of mind games people can play on kids (which even other kids can), which you don't need to worry about if you are just a random guy, but do need to, if you are controlling a community/country.