I can't read the OCRegister article but the Laguna Beach Indy news site reports concern for traffic:
https://www.lagunabeachindy.com/laguna-sues-county-great-park-development/
"A significant portion of the project?s traffic will travel the streets and highways within Laguna Beach,? Laguna?s attorneys wrote. ?Other project impacts as well will be exported to Laguna Beach, contributing significant cumulative impacts that adversely affect [the city.]?
Looks like Laguna is leaning on a previous measure W where "Orange County voters agreed to scrap the idea of building an international airport on the former marine base and instead dedicate its 4,700 acres to
educational, recreation, habitat and compatible uses." Laguna must not feel building 2,100 dwelling units, 220,000 square feet of retail space, nearly 1.9 million square feet of office space, and a 242-room hotel qualifies as educational or recreational.