If it turns out he is innocent it's going to look like a failed political hit job. In fairness to Salmond I can understand why he's challenging the process.
Wings posted this link last week, it's a blog post by a very prominent pro uk, snp and alex salmond hating commentator called Effie Deans. It's very hard to argue with the conclusions she draws and given her political leanings I think it says a lot that she supports Salmond challenging it.
https://www.effiedeans.com/2018/08/we-must-also-defend-opponents-from.html?m=1