Reeves didn't struggle with the arresting deputy. It was an off-duty deputy from another county (Sumter Co.) who was seated near Reeves in the theater. He gained possession of the weapon and detained Reeves until local LEO arrived.
Oh yes he did struggle.
From a linked article:
Cpl. Alan Hamilton, an off-duty Sumter County sheriff’s deputy who had come to see the movie with his wife, secured the weapon and detained Reeves, the sheriff’s office reported.
...Hamilton identified himself and grabbed the barrel of the gun, Greiner said. Reeves resisted initially, but then let go of the gun, Greiner said.
...Greiner said the gun was jammed and could not have been fired again. He was unsure whether Reeves planned to fire a second shot.
IMO he’d have popped off the whole clip if it hadn’t jammed. And just as likely would have shot the deputy too! Otherwise why resist?
IMO he crossed the threshold of murdering a cell phone user long before entering the theater.