When a Buddha acts in ways that we do not expect a Buddha to act:
Option 1: our faith is weak and we stop seeing a Buddha, what we see is a being defined by the challenging action that this being is doing or has done. Result: we either move backwards or we remain stationary (which equates to moving backwards).
Option 2: our faith plays its true role (it remains and keeps our minds virtuous when expectations of actions and results have been disappointed and when hopes have dissipated), what we see is a Buddha in action taking a student (me) through testing grounds, or blessing a student (me) with a teaching, or making a student (me) purify black karma, or making a student (me) unknowingly participate to the growth of Dharma through a student's (my) delusions (let's talk about skillful means!).
What makes a guru?
A guru can only be a guru in the eyes of his students that have invested faith in the guru having the qualities of a guru. The guru will challenge his students' faith, it's his job. As the guru tests his students, some student's faith will show to be strong and will grow stronger and some students' faith will be weak and will weaken further if an antidote is not applied quickly.
The moment a student stops investing his guru with the qualities of a Buddha, his guru cannot help him much any more, and as a result the faith weakens even further, this is a very saddening process.
I take an example to illustrate the above: the 6th Dalai Lama.
Some very powerful people then lost faith in His Holiness, they stopped seeing a Buddha and only saw someone who seemed to be principally interested in courting ladies. Because of the faith being lost, they engaged in actions that created obstacles for them to benefit from His Holiness.
Would their faith had remain, the modern history of Tibet would have been very different indeed.
We only need to look in the past to see how loosing faith in His Holiness had proven to be unwise, and in the light of that, re-consider what is happening today with a broader point of view.