Basically, the speakers say that the Quran does not lay down a punishment for apostasy. I think that is false. However, Islamic law and practices are not derived solely from the Quran. And when one takes into account the other sources, the punishment for apostasy becomes even more clear. (I wrote about this subject in 2005.)
They but wish that ye should reject Faith, as they do, and thus be on the same footing (as they): But take not friends from their ranks until they flee in the way of Allah (From what is forbidden). But if they turn renegades, seize them and slay them wherever ye find them; and (in any case) take no friends or helpers from their ranks.
See Ali Sina for the context.
The other source: Sahih Bukhari, Volume 9, Book 84, Number 58:
[...] There was a fettered man beside Abu Muisa. Mu'adh asked, "Who is this (man)?" Abu Muisa said, "He was a Jew and became a Muslim and then reverted back to Judaism." Then Abu Muisa requested Mu'adh to sit down but Mu'adh said, "I will not sit down till he has been killed. This is the judgment of Allah and His Apostle (for such cases) and repeated it thrice. Then Abu Musa ordered that the man be killed, and he was killed. [...]
One can argue that the Quran doesn't punish apostasy. But then what about the horrible precedent set by the hadith?
Here's another one: Sahih Bukhari, Volume 9, Book 83, Number 17:
Allah's Apostle said, "The blood of a Muslim who confesses that none has the right to be worshipped but Allah and that I am His Apostle, cannot be shed except in three cases: In Qisas for murder, a married person who commits illegal sexual intercourse and the one who reverts from Islam (apostate) and leaves the Muslims."
Quite clear, innit?
"There is no compulsion in religion" [Quran: 2.256] means that we do not compel anyone to come into our religion. And this is truly our practice. But we initially warn whoever would come and go back that this door is not open to come and go. Therefore anyone who comes should decide before coming that there is no going back.
Well, what about those who are born to Muslim parents?
[...] children born of Muslim lineage will be considered Muslims and according to Islamic law the door of apostasy will never be opened to them. If anyone of them renounces Islam, he will be as deserving of execution as the person who has renounced kufr to become a Muslim and again has chosen the way of kufr. All the jurists of Islam agree with this decision. On this topic absolutely no difference exists among the experts of shari'ah.
What conclusion does one make about a religion that practically imprisons every one of its adherents?
Simple: Islam is a decrepit system built on putrid foundations. It has to murder its opponents for it cannot survive in the arena of open debate. Terror is built into its DNA.
This ugliness presents a massive problem for moderate or "diet" Muslims. So, they pick and choose what they like.
An analogy would be a restaurant that serves the most disgusting courses. Authentic or "pure" Muslims gobble every single item to showcase their street-cred to the rest. The moderates show a bit of discrimination and pick the less noxious meals.
It's one thing to do that but it's quite another to then turn around and deny the existence of the filthier items on the menu.
It makes the moderates look ludicrous and intellectually lame.