Why was a Nebulon-B medical frigate at the Battle of Endor?

Question

So rewatched the final battle scene from Return of the Jedi last night and caught the line:

They’re heading for the medical frigate!

It’s something I never thought about before since seeing the film in the there in 1983, but here is a seemingly obvious question:

Why would the rebels bring a fairly defenseless medical frigate into battle like that? And is there any canonical discussion or allusion to the rationale behind the deployment of a medical frigate to a large scale battle like that?

This thread on Rebel Scum theorizes many things such as:

• The rebels believing that the assault on Death Star II would be a “milk run” so they brought the medical frigate to deal with limited casualties. They generally saw the assault as a hyperspace jump in, attack & destroy and hyperspace jump out endeavor.
• The Nebulon-B was a medical frigate yet still had significant assault and defense capabilities since as the Wookieepedia states, “The EF76 Nebulon-B escort frigate was a 300-meter-long warship that was built by Kuat Drive Yards for use by the Imperial Navy, to protect convoys from Rebel Alliance star fighter actions.”

But looking at that same article on the Nebulon-B at the Wookieepedia seems to contradict itself under the “Variants” heading; emphasis in bold is mine:

The Rebels converted some of their Nebulon-B frigates into medical vessels, which served as mobile hospitals. Weaponry and hangar space was sacrificed to make room for treatment facilities, 15 bacta tanks, 745 beds, and other hospital suites. The crew was slightly modified to included an additional 80 medical personnel and 30 medical droids (such as the 2-1B model). These ships could not carry any fighters, and their armament was reduced to 6 turbolasers (with computer-assisted targeting) and 8 laser cannons.

So the Nebulon-B medical frigate at the “Battle of Endor” was truly a sitting duck of a “battleship” if it was retrofitted into a medical frigate, correct? It was significantly reduced of it’s core offensive/defensive capacity, right? Then why was it there? And does anything in historical canon of the original trilogy—such as novelizations and such—address this issue?

Answer 1

After some hunting, I finally found a solid reference on why the "Medical Frigate" (later named in the EU novels as The Redemption) was at the Battle of Endor;

The Star Wars Technical Journal not only offers an insight into the ship's relatively formidable weaponry (6 banks of Turbolasers and 8 banks of lasers as compared to the Mon Calamari Cruiser's 48 banks of turbolasers) but also into the reason why the rebels would take the vessel into danger:

REBEL MEDICAL FRIGATE

Any military effort, sadly, involves injury and death for those engaged in it. For this reason. The Rebel Alliance, unlike the Empire, has put a high priority on the availability of medical attention at the site of conflict. By converting a Nebulon-B escort frigate from its standard hangar/starfighter launch bay configuration, the Rebel forces have made it possible to save the lives of many of the brave pilots and crew members whose lives are dedicated to the struggle against the Empire.

This hospital ship travels with the fleet, often directly into combat situations. Its cluster of intensive care units, recovery wards and operating theaters can treat over 700 patients simultaneously, with a recovery rate higher than many planetside hospitals. The Rebel medics aboard are highly-trained in the field treatment of blister wounds, chemical poisoning, fractures and vacuum exposure, and can stabilize any more serious wound until the patient can be treated by a more fully-trained doctor or medical droid.

Waiting time for treatment is minimal, and most pilots are ready and anxious to return to flight within a couple of days. The survival rate of patients following treatment has remained near 98 percent, so any patient who can reach the Medical Frigate is almost assured of staying alive.

Answer 2

As a matterof speculation, I would say the Alliance did not have the manpower the Empire had - they could not afford to sacrfice skilled personnel in the same way.

Also, the frigate is still an armed capital ship with a working hyperdrive. It provides some hope of evacuation if things go south.

Answer 3

Why was a nebulon-B a medical frigate in the first place? The rebels obviously had an extensive shortage of ships in comparison the the Empire, to the point that they were taking cargo ships and decking them out as warships. A ship such as the Redemption was a huge complement of firepower compared to a modified transport ship. Why not use an old cargo ship as a medic frigate? They're just huge empty chambers on engines anyways so they're ideal for retrofitting.