What is the purpose of the underlined line, "When that the poor have cried, Caesar hath wept"?

The key to interpreting this line is found on the very next line: "Ambition should be made of sterner stuff." Mark Antony is implying that ambitious men are "stern" that is hard and unlikely to cry. However, Caesar did in fact weep with the poor. Therefore, he is using the example of crying to try to show that perhaps Brutus is not correct in making the claim that Caesar was ambitious.