Should have been IBM Tom, after legendary IBM CEO Thomas J. Watson. But perhaps they didn't want to sully his name.

As somebody already mentioned, they already had a big product named after their CEO. IBM Watson was the next big thing after Deep Blue, and it went pretty viral after defeating Ken Jennings and Brad Rutter on Jeopardy back in ~2011.

It was a bit of a market play and of course has since been completely upstaged by the invention of LLMs, but it still definitely got them the attention they wanted at the time.

https://www.ibm.com/history/watson-jeopardy

IBM already have IBM Watson which is probably named after the CEO

IBM Wat?