It is a sensible combination to me. If you first believe that the government should provide a bunch of free stuff, but it doesn't at the moment because it's too expensive, it kind of makes sense that you would then think there need to be fewer people getting the free stuff so it remains affordable. The first people on the exclusion list would naturally be noncitizens.

Also they are anti EU and NATO. Lot of astroturfing here.

its not uncommon. The overtly racist parties in the UK (e.g. the BNP has quite a lot of left wing policies (e.g. nationalisation of utilities), ending NHS outsourcing to the private sector, and free healthcare.

Its a combination that appeals to the worst off who compete with unskilled immigrants for jobs and rely on free healthcare etc.

As it turns out you can't have strong socialist policies and also open borders.