I don't think Spinball has ever been a 'problem' from a legal or planning perspective in the past, it was always Oblivion that got mentioned in Court so it may not carry much weight in that regard - though it's not secret management hate the ride so I do agree it's days are certainly numbered.
Plus, I really wouldn't want Towers to set a precedent for a 'one in, one out' policy with the council by removing a significant attraction just to get permission to build something new. There are much better compromises that could be made, ones which would benefit the council, locals and the park which I'd guess the council are more likely to look more favourable upon. Things like improvements to local road infrastructure, a commitment to revisit the bypass plans, investment in public transport links that could benefit the community all year around, etc.