DISCLAIMER: For the purposes of the following article I'll be operating under the assumption that the so-called "Patoshi Pattern" is, in fact, a single miner entity and that this entity was Satoshi. As such, I shall use "Satoshi" and "Patoshi" interchangeably. While it is not possible to prove this claim beyond a reasonable doubt, the behaviors exhibited by this miner suggest someone with an extremely deep knowledge of Bitcoin very early in its existence - a Satoshi-level understanding. But that's a topic for another post.
See? Even in the sources you linked, there is still some doubt, if Satoshi=Patoshi. And I think it is not the case, for example because the Genesis Block does not match some patterns.
Also, each time, when extraNonce was resetted to zero, then you can have this miner, or that miner. And the way of mining also changed over time.
I don't know that 20,000 inputs is a threshold
1 MB legacy transaction size is a threshold. If you have 1400 UTXOs, then you have 70k coins. That will give you a transaction of slightly below 100 kvB. So, for 14,000 UTXOs, you can potentially move 700k coins, maybe 750k coins, if they are all P2WPKH inputs. But: because of legacy P2PK or P2PKH, it will take much more space than that.
there are very few transactions that have 20,000 inputs
Note that you will need a regular DER signature, for each individual input. And note that you cannot use a Segwit discount, because it didn't exist at that time, and you had only P2PK or P2PKH. So, you will need at least a few blocks, to even combine all of those coins, even if you solve everything at once.
Only 9 transactions have 20,000 inputs and there is no block with more than 20,000 inputs.
Well, 20k inputs in a single 1 MB legacy block space, would mean something around 50 bytes per input. It is hard to get DER signatures that small. The smallest valid ones take 9 bytes, and you would need the private key for x-value pubkey below 0x80 (which is very hard), and around 2^249 s-value grinding (which is also extremely hard). Even exploiting SIGHASH_SINGLE bug will force you to grind a lot of SHA-256 transaction data, to get 9-byte signatures, because for around 128 valid s-values, and around 64 valid r-values, you will get around 8192 matching keys, so even if you prepare non-random pubkeys upfront, it will be hard to get there.