French Presidential Election

[Husar]

Relevant diseased individuals are isolated because of their potential to infect others in general, not because they already have infected people. Similarly, certain demographics can be 'isolated' to avoid the spreading and/or induction of terrorism.

There is an incredibly large gap between infected individuals and potentially dangerous demographics.
That argument is completely useless. You could lock all poor people up with that argument.

If elderly people were mowing down many people every now and then because of poor driving skills, and the major political parties suggested that scepticism against driving elderly people was driven by gerontophobia, you might get the rise of political parties that suggested restrictions on the driving of elderly people.

We had 3300 traffic deaths and maybe 20 due to islamic terrorism in 2016. Now I don't have any statistics on who caused all the traffic deaths and why, but surely old people would account for 20 or more of them?
The rest of your argument seems pretty irrelevant to the argument.

Of course, it's not just the terrorism that's a potential issue with mass-immigration; but local breakdown of law and order as well. A good case study is the Swedish city of Malmö (click the link to see more news items), a city with ~ 340,000 inhabitants:

I get that you can't just put 340000 immigrants into a city of 340000 people and expect it to work out just fine, that is actually besides the point now. Just as it is useless to take one city as anecdotal evidence and then make some vague claim about how problematic mass immigration is.