I'm not sure that would have been a motivating factor for Satoshi. Was a "pre-mine" even a concept which existed prior to altcoin creators using it to make themselves richer at the expense of their users? Would Satoshi even have known of the concept of "pre-mining"? If he was overly concerned about being seen to be pre-mining, then it doesn't make sense for him to have mined the first block 5 days prior to announcing the release of the software to the mailing list.
And you could equally argue that the genesis block isn't a pre-mine; it's a regular mine. Pre-mining is setting aside x amount of coins before your chain is even launched. The genesis block wasn't that, but rather the standard block reward for mining a block. It just so happened to be the first block.
The basic concept of a pre-mined coin is "coins that were produced in an unfair way when one party has all the advantage". In other words the fact that nobody else could mine block 0 and Satoshi mined it in private makes the reward of that block "pre-mined". I'd say that the fact that he mined the block doesn't change that.
In contrast block 1 could have been mined by anybody since the software was released and the network was live before the block was found, which makes the rewards of blocks 1+ fair distribution.
What pre-mined altcoins do is the same thing, they just remove the effort to mine a valid block by summoning the coins out of thin air but the principle of "coins created in an unfair way" is the same.