NEW YORK — Elon Musk's public endorsement this week of a potential $3.5 trillion merger between SpaceX and Tesla has rattled some insiders involved in the discussions, who worry his comments could invite shareholder scrutiny and delay the process by several weeks, according to a person with direct knowledge of the talks. The disclosure created a "mess" for the process, as it could lead to questions about how well Tesla shareholders' interests would be represented, the person said. The concerns reflect similarities some participants see with Tesla's 2016 acquisition of SolarCity, which sparked years of litigation over Musk's role in the deal. Musk, who serves as CEO of both SpaceX and Tesla and owns significant stakes in each company, this week told investors that the two companies were examining what would be the largest corporate transaction in history and revealed that both had formed special committees to evaluate it. The backlash to those remarks is reported here for the first time. The parties have hired advisers, but discussions are at an early stage, three sources familiar with