I'm very pro-immigration, and I would not support allowing large numbers of Palestinian refugees into the UK.
Contrary to what the article says, we do have a reasonable idea of what Gaza residents think of Hamas and the attacks, because it gets polled regularly, including by Palestinian-run polling organisations.
The latest data I could find:
71% of Gazans support the October attacks on Israel (see link)
5% believe that Hamas committed war crimes (separate poll)
Many countries in the region have given shelter to Palestinians groups at one time or another, and regretted it because it destabilised their politics.
www.pcpsr.org/en/node/969
I am a strong supporter of increased immigration, on economic grounds, liberty grounds, and humanitarian grounds. For that to be democratically legitimate and politically feasible it must be, and be seen to be, beneficial, or at least benign.
Mass migration from a deeply traumatised population the large majority of which (71%) support a terrorist slaughter is not going to help that. If I had grown up in Gaza, I'd probably be amongst the 71% (no reason to believe I wouldn't be). But that doesn't change the risk profile.