by confirmed information from a known source, that the US choppers were detected by Syrian air defenses - which is why I used "assuming arguendo".

The "detection" factoid is in the Sunday Times article.

Note this was a Sky scoop from an Israeli analyst - now running on Fox's ticker and the bottom of the hour news (22:30 EST) - so, one of Rupert's products, which does not necessarily damn it:

..... The Syrians, who had agreed to turn a blind eye to a supposedly quiet “snatch and grab” raid, could not keep the lid on a firefight in which so many people had died.

The operation should have been fast and bloodless. According to the sources, Syrian intelligence tipped off the Americans about Abu Ghadiya’s whereabouts. US electronic intelligence then tracked his exact location, possibly by tracing his satellite telephone, and the helicopters were directed to him. They were supposed to kidnap him and take him to Iraq for questioning.

According to defence sources [JMM: whose "defence sources" ?], when the four US helicopters approached the Syrian border, they were detected by Syrian radar. Air force headquarters in Damascus was asked for permission to intercept.

After an Israeli airstrike against a suspected nuclear reactor in the same region last year, Syrian air defence has been on high alert. The request was turned down by senior officers because the American operation was expected.

It is not clear what went wrong, but it is believed that the helicopters were spotted by the militants on their final approach and a gun battle broke out. That is supported by an account from a local tribal leader, who said a rocket-propelled grenade had been launched from the compound at the helicopter. The firefight blew the cover on a supposedly covert operation.

Ninety minutes after the raid, according to a local tribal leader, agents of the feared Mukhabarat, the Syrian intelligence service, flooded into the village. “They threatened us that if anyone said anything about what happened in this area, their family members would die,” he said.
The bolded lines had to have had an origin in Syrian defense communications (if they are true); but could have been intercepts, or whatever else you wish to imagine, as the chain of transmission.

There has been more (apparent) substance added to this story as it goes along.

The eyewitness testimony of the villager (again if true - I sure didn't interview him), as to Syrian Intel being on scene within 90 minutes, is also interesting.