Incredibly stupid move by Cates....
Giving up his gun to Gans in the hotel lobby standoff. Beyond stupid!
He had them at a standoff.....there was already lots of gunfire...so cops were sure to be there soon. Cates knew Gans and Billy had to get the heck out of there quickly--they didn't have time to waste in a standoff. Cates may have been at a disadvantage with it being 2 against 1. However, time was on his side. He just needed to remind them...they only had a couple minutes to get out of there before the building would be surrounded. Then...tell them...if they'd let the hostage(s) go, he'd let them escape.
He was still at a disadvantage. But better to be at a disadvantage with a gun...than be at a disadvantage without one. Use your negotiation skills, and be ready to fire.
Giving Gans his gun was suicide. He lost any leverage he may have had.