He was never pro-Russia, but pro-UK, pro-Nike, pro-Paula, pro old-boys-network, anti-transparency, and against criminalization of doping, and always looked out for himself first, see e.g. his lobbying on behalf of (his then employer) Nike to his "spiritual leader" Diack while being his VP (which he denied of course).
If he was so corrupt then why take the hard stance against Russia, resulting in death threats to him and his family? If he hadn't banned them he'd be damned and criticised, and by banning them he is still being damned. He can't win.
Standing up against Russia helped the UK and his personal and professional reputation. No surprise there.