Klinghardt:
Marcion would have surely removed the pericope about "why do you call me good? Only god is good" since only YHWH is meant. The fact that he didn't proves that Marcion didn't mutilate Luke.
Bermejo-Rubio:
The evangelists would have surely removed embarrassing disiecta membra (= scattered fragments) proving that Jesus was a violent anti-Roman seditionist. The fact that they didn't proves that they weren't embarrassed by the preservation of such material.
Conclusion: it is therefore possible, even expected, the preservation of embarrassing material.
