I don't think that is what the Professor is suggesting at all.  He is right in that tough talk isn't going to do much, that the number of resources needed to monitor high risk individuals is prohibitive, and that internment without charge would almost certainly make things worse.

I think that stepping up anti-terrorist measures to the extent possible (without violating the freedoms of the law-abiding) and summary deportation or prison terms for those who are caught plotting schemes are the only short-term actions available.

If the UK were to permit unlawful search and seizure and impose curfews and other measures, they will have already lost to the extremists.  Disruption of society is precisely what terrorists want.

But dialogue, education, and perhaps a little more sensitivity when dealing with Muslim nations will help over the longer term.  Harsh measures not based in law will not work -- they never do.  And vengeance has no place in the legal system of a civilized country.