if talking about meme coins, then we can compare doge coins and shiba coins. of course shiba has a very large supply of coins compared to doge. so it is very unlikely that Elonmusk keeps shiba, as far as i know shiba is just hype coins and nothing more. and I think BTC has become the main asset priority that Elonmusk has. moreover he owns a Tesla company and he also accepts payments via BTC.
As for Elon asking if he owns SHIB then how we would able to know? He doesnt necessarily tell the public on which coins he had been accumulating and holding.