I don’t think that the time or score affect the drops. I have finished it a few times myself and was discouraged with no drops too If you find a really cooperative group in the future you can drop the time down to around 40-45 minutes, which makes it feel a little less like a let-down.
I believe their intentions for that part of the fight were to fight the Foreman Grall while also putting up the turrets so that they did damage while you were whittling him down. I haven’t had a perfectly put together group myself so I haven’t really wanted to run the risk and put them up and “accidentally” have 2 bosses aggroed at once.
Now the knock-backs that every boss has on that part…oh boy don’t get me started.