BZ's Urdu is not very good, (for that matter neither is IK's) but former's is far worse than the latter's.
In fairness, Bilawal speaks in the language he is most comfortable with and not just to show off. The same, as an example, goes for IK's son Suleman. One can hardly blame either of them for not being too eloquent in Urdu because their parents "chose" to have them educated and live in the UK.
On the issue of BZ's appointment to the office of the FM, can you remind me what type of "global celebrity" or "merit" SMQ had earned for him to be put in the office of FM? He is a politician from a feudal family like the Bhuttos/Zardaris. As I have stated before, all FM's in Pakistan are political appointees and most come with no "merit" to lead the FO which is unfortunate but also the reality.
I think people are making too much of this situation.