That’s a weird request And a dumb reason to ban a movie.
UK DVD and VHS releases of The Abyss was cut for same reason
Reason is UK 1937 Cinematograph Films (Animals) Act
BBFC are strict on this
Exceptions are
Example a documentary showing animals in distress or be killed or get injured is
something that would have taken place regardless of whether or not it had been filmed.
Another example where the act did not apply
Apocalypse Now
The animal slaughter scene in that film (a water buffalo, or carabao) was killed -
but not for the film. The tribe in the film was a real indigenous tribe that lived in the area, and they had already decided to slaughter it. Coppola merely decided to film the event and edit it into the film
This latter point of the act largely applies to documentary producers, though scenes such as the climactic sacrifice in Apocalypse Now (US, d. Francis Coppola, 1979) have also benefited.
The Abyss is different because it was a film that deliberately shows causing distress to a animal and not a natural event that's not allowed under the act
The Abyss rat scene it's not something that would have taken place regardless of whether or not it had been filmed.
It's not a natural event it was done deliberately for the film
The rat demonstration scene in The Abyss was unsimulated and used real-life oxygenated breathing fluid
Lightstorm should have allowed Disney release cut version on Blu-ray and UHD in UK