Twitter argued Musk's attempt to pull out of the deal is motivated by protecting his financial interests as stock markets cool, rather than any valid concerns over bots.
Tuesday's wide-ranging hearing, in front of Chancellor Kathaleen McCormick, also covered Musk's request to amend his lawsuit so he could update it with the claims of a former Twitter executive turned whistleblower, who alleged last month that the company had misled regulators and investors about its user security practices.
Musk had asked to delay the five-day trial scheduled for October 17 for a few weeks to revise his lawsuit and conduct further discovery.
Lawyers for Twitter dismissed Musk's efforts to delay the buyout as "an expensive and gruelling fishing expedition", arguing the accusations from Peiter Zatko, the former head of security at Twitter, could not meet the legal standard to nullify the merger contract even if they were true.
Twitter conceded Zatko raised concerns earlier this year about cyber security practices to senior executives. However, lawyers said these were investigated internally and "found to be without merit".
Musk's lawyers accused Twitter of blaming the billionaire for its own misconduct, arguing that it had the right to seek out further information on the matter.
Limited due diligence ahead of agreeing to a transaction is "what Warren Buffett does when he buys public companies", Musk's lawyers argued. "Nobody seems to give Warren Buffett the same reaction when he does it."
Separately, Twitter had also asked the court for Musk to be sanctioned for delays in producing text messages, which they said amounted to misconduct.
The platform had also asked the Delaware court to force Musk to turn over his emails with lawyers that he wrote using Tesla and SpaceX accounts, which they said were not subject then to the attorney-client privilege.
Both Twitter and Musk acknowledged the intensity of the preparation for an October trial, which has included dozens of subpoenas and information requests as well as depositions that have begun.
McCormick did not immediately rule on any of the matters.
-By Hannah Murphy in San Francisco and Sujeet Indap in New York