No, it wasn't just internment and the first prisoners were politicians he disagreed with. Nor were these similar to the normal wartime internment camps. They had a particularly brutal and violent regime. People were sent to Sikorski's Polish Concentration Camps for all sorts of reasons including ethnicity and sexuality.
A very interesting book was published recently. There are even a tiny number of survivors of Sikorski's evil camps who are still alive.
In times of war, decisions do indeed have to be made quickly, however the law still applies, as does basic human decency which Sikorski lacked.
Some interesting links here:
Who was in it? For example, the former prewar Prime Minister Marian Zyndram-Kościałkowski, the commander of the Army "Prusy" General Stefan Dąb-Biernacki, the governor of Silesia and the president of Polish Scouting Association Michael Grążyński and others.
secretscotland.org.uk/forum/m-1308564097/
Between 1940 and 1946, a number of concentration camps were set up on the edge of large towns; some only a few miles from major cities. Local farmers heard rumours about atrocities being committed in these places, but when they approached the barbed wire fences, they were warned off by armed guards in watch-towers. Stories circulated about beatings, torture, starvation and even shootings, but so secretive were those running the camps that no solid information ever leaked out. It was also suggested that these sinister locations were being used to hold communists and homosexuals
thejc.com/comment-and-debate/essays/152262/life-inside-concentration-camps-scotland
"Those who do intrigue, will be sent to a concentration camp "- Władysław Sikorski