Is it not obligatory for scholars to advise Muslim rulers in this era, given the rampant spread of corruption, or does the fear of people outweigh the fear of Allah?

Muslim scholars, past and present, have been and continue to be committed to advising rulers and their subjects. Many of their stances on this matter are well-known, while others are not publicly disclosed for the sake of expediency, as confidentiality makes the advice more likely to be accepted. It is inappropriate to harbor ill thoughts about scholars and to claim that they have abandoned their duty of giving advice and speaking the truth.

And Allah knows best.