Propofol is a severe respiratory depressant, Ativan can do the same but is dose dependent, 1-2 mg Q1H is reasonable. Think of your CIWA patients; you wouldn't be allowed to push 4mg Q1H if it caused severe respiratory depression in every patient.
Someone on PSV should be sedated with another drug. You can argue Morphine is a respiratory depressant too, heck seems like all our drugs are, but Propofol is a heavy hitter. PSV makes the patient work to breathe, you can breathe the rate/TV on A/C and put no effort forth if you want.
Sounds like your pulmonary doc was more concerned about getting the guy extubated since he didn't really have a respiratory issue beforehand (just surgical), but he was being a bit laissez-faire about his BP and agitation. Someone with fluid overload who is too awake is going to be agitated as all get out (granted he needed it and it wasn't just replacements in surgery, but a laparoscopic shouldn't require you to need 6L replaced if I'm not mistaken). If he really wanted the guy extubated he should have come to see the patient and decide whether he could wait a day to be extubated, start a Lasix gtt, something.
Good on you for calling again and again. Hope you documented your butt off though!