The intersecting runway may be shorter so it could accommodate a smaller regional jet, leaving the longer main runway available for larger aircraft.
On final approach, on glideslope, and reportedly 30 seconds from landing, changing from a 33o degree approach to a 10 degree approach is a major operation - probably with a go-around, procedure turn, and other maneuvers.
The helicopter should have been turned away, by the pilot if not the ATC controller, IMO. (Not a pilot, but in aircraft industry with ground school under my belt).
“The intersecting runway may be shorter so it could accommodate a smaller regional jet, leaving the longer main runway available for larger aircraft.”
That is exactly what I’ve read.