Leagues clubs have underfunded and refused to bail out failing clubs in the past, so why not in the future.
For years Parra had a running battle with their leagues club over funding, and Tweed ended up cutting their losses rather than continue to throw money at the Seagulls. Though not a leagues club, there was a time in the 90s and early 2000s when South Juniors were significantly more wealthy comparatively to Souths football club, but refused to give them grants or loans despite knowing that it'd probably lead to Souths going bust sooner or later.
Some people would argue that some of the current leagues clubs run their NRL sides as cheaply as possible, I've definitely heard people level that accusation at Wests Rosellas for example. I couldn't say whether or not that's a fair accusation in that case though.