Meta Platforms is urging California’s attorney general to block OpenAI’s planned conversion to a for-profit company, siding with Elon Musk in a battle between Silicon Valley’s most powerful artificial-intelligence players. In a letter to Attorney General Rob Bonta dated Thursday, Meta said allowing the ChatGPT maker to become a for-profit company would set a dangerous precedent of allowing startups to enjoy the advantages of nonprofit status until they are poised to become profitable. “OpenAI’s conduct could have seismic implications for Silicon Valley,” Meta wrote in the letter.