Not sure if this will be helpful, but these are questions I would ask the Vet
1- What diagnostics were carried out to try to find a primary cause of the gut stasis? Gut stasis is usually a SECONDARY SYMPTOM rather than an illness within itself. I would expect a Vet to suggest running a full blood profile, this could flag up problems with the liver and/ or kidneys, signs of infection, amongst other things. Diagnostic imaging eg abdominal X-rays/ CT scan. A urinalysis. A full dental examination. Although a GA is required to obtain a 100% view inside a Rabbit’s mouth.
2 - If any of the above were not carried out, why not ?
3- Did Sweep go into cardiac arrest AFTER receiving sedation for the exploratory surgery, or did it occur prior to any sedation?
4- On admission what were the exact clinical findings ? What made the Vet suspect a Liver Lobe Torsion at that point, after 2 weeks of recurrent consultations rather than earlier on ?
It could be that sadly you will never know why Sweep died. Which does make processing the loss more complicated. If he were my Rabbit and I was told he went into cardiac arrest after receiving sedation for the surgical procedure I would consider that he passed because he reacted badly to the drugs, probably because he was already very sick. Even an apparently healthy Rabbit can have an adverse reaction to a GA, any animal can. As can any human. There is no such thing as a risk free GA. But if the Rabbit is already very unwell the risks will be greater. But a risk that had to be taken as doing nothing was not an option.
I hope that speaking with the Vet will be of some help.But I completely understand that the only thing that could really help is the impossible, for Sweep to still be with you