@gungasnake,
I don't think we can say that our societies are not enriched by immigrants from "Muslim countries," simply because one of the greatest threats these societies now face is terrorist Muslims.
However, it has already become necessary, in the US, to balance the value of one against the danger of the other in terms of immigration law, and it appears the UK should do so as well.
It is unfortunate that all Muslims can be easily painted with a broad brush as extremists, but as long as some Muslims plan and operate in secrecy to kill our citizens and destroy our infra-structure, all Muslims will be logical suspects...if not to the authorities, then surely to the people.
In addition to dealing death and destruction, the Muslim terrorists also sow distrust and fan bigotry. It is all well and good to say that we should not blame all Muslims for the evil of a relative few, but at some point it is possible for the rationality of that plea to be overcome by waves of fear and outrage.
Foiled plots like this one are scary and sobering, but they don't have anywhere near the same impact on the public psyche as executed attacks. Thankfully this plot was discovered and thwarted, and as long as that track record continues, the uneasy relationship between Muslims and non-Muslims in the UK and the US will not degenerate, and the mutual benefits of immigration and cross cultural interaction will continue. However, as long as Muslim terrorists remain bound and determined to attack the West, it is unlikely that the authorities will be able to uncover and stop all of their planned attacks.
Should a series of escalating attacks prove to be successful, in the terms of their perpetrators, and result in significant death and destruction the very real benefits of immigration will become a casualty.
One would think that the innocent Muslims who are thriving thanks to the benefits of immigration to the West would understand this better than the rest of us. When you are in a minority of any sort, you have a heightened sensitivity to how any member of your minority relates to and is perceived by the majority simply because there are concerns about being tarred by the same brush.
I seriously doubt these thriving immigrants believe that they cannot be impacted by an increasingly fearful and outraged native population; that their hosts believe that they need the guests more than the guests need them.
I'm sure that most of the them appreciate that their lives will be different in important ways, if the threat of Muslim terrorists was eliminated tomorrow. To that end, I would like to think that for reasons of self-interest, if none other, that they are assisting the authorities in their host countries to identify and stop these planned attacks.
Perhaps the primary source of intelligence behind this successful action was one or more thriving and innocent Muslim immigrant. I hope so.
I would, however, have a greater confidence that this war can be concluded and won, if the innocent Muslims in the UK were more vocal and demonstrative of their opposition to the goals and methodology of the Islamists. Perhaps they are more that I know, but I like to think of myself as a well informed person in terms of current events around the world, and I've not seen the evidence. Perhaps the media isn't covering it as they should, which would be a shame, but not entirely out of character for them.
In the meantime, well done UK authorities. I hope your efforts are sufficiently appreciated in your country.