Can you explain why someone from Hull would delight in their hometown club in any sport being in trouble a joyful thing?
Certainly, although you probably need to be a local to fully grasp the situation but I'll give it a go.
Hull City Council built the KC Stadium for the people of Hull. It was intended to be a facility in use all year round, with leases granted to both Hull City and Hull FC to allow them to play there, but also a facility to host pop concerts and the like and plenty of office and conferencing space for use by anybody wanting to hire them.
The stadium needed a body to run it so the Stadium Management Company (SMC) was formed and both Hull City and Hull FC were invited to join the SMC board for a fee. At the time Hull FC was being run by people with no long term interest in the RL club so they didn't want to spend any cash and turned the offer down. This was a fatal error for the RL club. Hull City took their opportunity, probably with some glee, and so now they are enjoying a 50 year lease during which whoever is the Chairman of Hull City is also the Chairman of the SMC.
Everything ran okay for a while until the football club were promoted to the top tier. The Premiership millions that this brought in attracted all sorts of unsavoury characters hoping to get their hands on some of it. It could be argued that, for a time, Paul Duffen was probably the worst. He stopped the concerts and treat the RL team and it's fans like they were lepers, once suggesting during a live radio debate that RL fans couldn't write. He wouldn't allow any RL internationals to be played at the stadium either, always saying it was "unavailable". During his tenure he was also accused of syphoning money out of the football club but this matter was apparently settled out of court. Russell Bartlett also seemed to have a chequered history whilst Chairman, apparently taking out a £4 million loan to help buy the club, seemingly using the stadium as collateral.
Then after a couple of seasons, the football club were relegated and once the money began to dry up, people like Duffen and Bartlett lost interest, Hull City's financial state took a drastic turn for the worse and they needed bailing out again.
Along came the Allams. They "bought" the club and apparently got it back on a relatively even keel, saying it cost them far more than they anticipated but, with Hull being their adopted home, they wanted to put something back into the city. It seems though, that all the money they've put in is actually a loan, and they are apparently earning interest on it all the time.
During the Allam's tenure at Hull City and naturally, the SMC, they apparently had a fall out with and sacked Adam Pearson who was still involved with Hull City as Director of football, held a consultancy role on the SMC and had recently bought Hull FC. Pearson reacted with surprise and anger at the sacking, but he was a big supporter of Nick Barmby who was Hull City coach at the time and had been sacked after suggesting the Allams didn't have the club's interests at heart. There was another apparent out of court settlement which Pearson afterwards said he was happy with and ended the matter.
Since that time, it looks like the Allams have taken it upon themselves to make sure they "get their own back" on Pearson, which obviously means the SMC giving the RL club a hard time. I'm not going to bother listing the recent stuff that's gone on, like I said earlier, you probably need to be a local to grasp it all.
It's fairly obvious that the Allams and plenty of the football club's fans want Hull FC out of, what they regard as, their stadium. Whilst they're in the Premiership with near capacity crowds when the big boys are in town and have all the money rolling in, they're in a fairly powerful position compared to their co tenants. When they get relegated and all that money and half decent players it attracts disappears, then they will be back on a similar footing to the RL club, or possibly far worse if recent history is anything to go by.
I've tried to remember stuff as accurately as I could in my explanation with a bit of Google help but if anyone can correct anything I've put then feel free to do so.
I hope that goes some way to explain my position.