There are of course two responses to this question. Firstly, it is perfectly possible to argue that Aeneas is presented as the prototype of the ideal Roman ruler, because of the epic nature of this text and the way Virgil is celebrating all that is good and powerful about Rome as a city and Romans as a people. Therefore, as the epic hero of the text, Aeneas is going to possess all that is strong and desirable about Rome himself. This can be seen in the text, particularly with repeated reference to "the pious Aeneas" and frequent reference to Aeneas being a character who respects both the gods and those around him. Note for example what he says to his father as they are fleeing Troy in Book II, when Anchises says he wants to be left to die:
Did you suppose, my father,
That I could tear myself away and leave you?
Unthinkable; how could a father say it?
Now if it pleases the powers about that nothing
Stand of this great city; if your heart
Is set on adding your own death and ours
To that of Troy, the door’s wide open for it.
This quote stresses the piety of Aeneas in a number of different ways. Firstly, it shows him to be somebody who has massive respect for his father because of both his status as a patriarch, but also the bond that unites them. Aeneas refuses to leave his father behind, even though this endangers his own safety, because he loves and respects his father. Secondly it shows Aneas to be pious through the way that he is presented as a man who accepts the will of the gods. This is the defining characteristic of Aeneas throughout the text, as he allows himself to be led by the gods and is responsive to their every command on his life. These are qualities that were prized in Roman times, and so Aeneas can be seen as the prototype Roman ruler.
However, at the same time, it is clear that Aeneas could be viewed as not being the perfect Roman ruler. The way in which he meekly submits to the gods and their plans for him, for example, suggests a certain amount of weakness. His role in his relationship with Dido as well, in one sense, is reprehensible, as he continues that relationship even though he knows that ultimately he will have to leave. It is difficult however to separate our own 21st century perspective of Aeneas from how the original audience of this text would have viewed him.