I don't think the problem is the assertion - even if the change of heart seems opportunistic - as much as the absence of acknowledgement of their own fallibilit

I don't think the problem is the assertion - even if the change of heart seems opportunistic - as much as the absence of acknowledgement of their own fallibility and their prior errors in world views. Granted, such an acknowledgement involves some degree of humility, but I think this is preferable to not having opinions at all, especially about issues that matter.