Fertitta Entertainment had moved to terminate the deal, first agreed in February, on Wednesday.
FAST said on Thursday Fertitta's delay in delivering its financial statements is why the deal has not been closed by the termination date, and so it has no right to unilaterally end the merger agreement.
Fertitta had in June expanded its agreement to go public with blank-check company FAST Acquisition Corp to include a few hospitality and restaurant entities.
The expanded deal implied an enterprise value of $8.6 billion for restaurant and gaming company Golden Nugget and restaurant-chain operator Landry's. The agreement announced in February had valued the combined entity at $6.6 billion.
(Reporting by Noor Zainab Hussain in Bengaluru and Echo Wang in New York; Editing by Krishna Chandra Eluri)