In the link you provided in post #5 there is a copy of an I-831 form that confirms he is being held for overstaying his visa. He entered the country under the visa waiver program which allowed him to stay in the US for 90 days. Even though he applied for asylum prior to his visa waiver expiring, he can still be detained and can be deported since he originally entered the country under the visa waiver program. Once the 90 days passed, unless there he was granted an extension or asylum beforehand, he became an illegal alien. Having a pending asylum case doesn't change this.
If he were truly seeking asylum, it seems he would have requested it as soon as he entered the country rather than wait until six days before his visa waiver expires; had he done this, in all likelihood he could have remained in the country without being detained until all his asylum hearings were heard and a final decision made. As it stands now, he will remain in detention until he is either approved for asylum (Highly unlikely), or deported.