Empty buildings to shelter Homeless in Portsmouth

Do I really even need to answer this?
I'll just tell you about a man I befriended a few years back, let's call him John. He was homeless. I got taking to him whilst waiting for the Gosport ferry after work one day. John was selling the big issue, he was clearly unwell. When I questioned him on his health he said is was "just a cold."
I'd bump into John at least once a week and as the weeks went on his health deteriorated. One evening I pretty much ordered him to get a bus to QA. I watched him get on the bus.
I didn't see John for the rest of that winter, then around April I saw him in North End. He was unrecognisable, he was a different colour, his eyes where shining, his hair was fuller and he was standing up straight. He had a girlfriend. He told me he that when he go to QA they all panicked over him. He had got pneumonia.
I am quite certain if John hadn't gone to hospital AND if he hadn't had a roof over his head whilst he recovered, he would have died.
It is also much less likely that he would have had pneumonia if he was not exposed to the brutality of a British winter.
If there is shelter in the form of empty or unused buildings, is it humane to deny it to those who need it the most?
This year 2,744 are estimated to be sleeping rough in the uk on any one night. This is up 14% from estimations on rough sleepers in 2013 and a staggering 55% from 2010!
Let's try and change that for the better!