When Michael comes to Frankie's house unannounced, he is scraming to him about how he was ambushed in his room where his wife sleeps and where his children come to play with their toys.

In the next breath he is telling Frankie he knows Roth was behind the hit and he enlists Frankie to help him take revenge.

So what is the point of Michael's outburst? It is unlike Michael to lose it the way Sonny did, and if he was already sure Roth was the culprit, he could not have been "testing" Frankie.