Well, what this Zindiq is not aware of (or most likely he is, it's just he tries to feed his gullible followers with an answer, for to them any answer is a good answer, they don't use their brains) is that although it is true that the Anbiyah had special rulings for them (like Qiyam being wajib upon the Prophet, or that he could take more than four wives) and that they have to obey what Allah orders them to do, yet:
1. There is no single evidence that in OUR Shari3ah we are allowed to marry non-believing women (except Ahl Al-Kitab).
2. The Shari3a of previous nations are no proof to us (otherwise we would greet our elders etc. by prostrating to them as a form of greeting, like in the time of Yusuf, peace be upon him, or how the Mala'ikah greeted Adam. This is haram in our Shari'ah.
3. Most importantly (and this is the Ayah I am talking about), the Qur'an has EXPLICITELY addressed the Prophet (then us of course), telling him that it is NOT allowed to marry a disbelieving woman:
So Al-Khabith's excuses about the Prophet marrying a Kafirah (Umm Al-Mu'minin as these kafirs claim), or the Prophet giving TWO of his daughters to Othman (who is a kafir acc. to them), or Ali giving his daughter to `Umar, are all void and nonsense, all he is doing is to disregard clear-cut muhkam Ayat and dwell into qiyas!
Sahih International
And do not marry polytheistic women until they believe. And a believing slave woman is better than a polytheist, even though she might please you. And do not marry polytheistic men [to your women] until they believe. And a believing slave is better than a polytheist, even though he might please you. Those invite [you] to the Fire, but Allah invites to Paradise and to forgiveness, by His permission. And He makes clear His verses to the people that perhaps they may remember. 2:221
Besides, Allaht told the Prophet to OPENLY fight the Munafiqs (and not to marry them and take them as close friends!):
Sahih International: O Prophet, strive against the disbelievers and the hypocrites and be harsh upon them. And their refuge is Hell, and wretched is the destination.66:9