Steel is suing the Mail for suggesting he take responsibility for Smith. He may even win, but that won't change things. Posterity is unimpressed by court judgements; it sees through them- and if it remembers Steel at all it will remember him as the party boss who tolerated Smith. The only way Steel can soften that judgement is by dropping the brat act and saying sorry.
That's all we want to hear from him at this point in time. We don't care about his blessed reputation (because what has he ever done that's of lasting significance?) All we want from him is an apology.