I've no idea who the OP considers to be in the wrong. It's my opinion that the police are in the wrong, certainly in the way they handled it, they have a very strange idea on what compassion is.
However the one thing that is not shown is what happened which required police involvement, did their daughter need taking for x-ray or other scans for example, if the parents were refusing to allow it then they were stopping the hospital staff from doing their job. It could even be COVID related, whilst that is not what their daughter was being treated for, there may be a case identified in that ward and so they need to test patients and move them to another ward. Without that
When he claimed of chest pains they should have called for paramedics rather than telling him he could go to A&E, he claimed to have medication so perhaps it would have been best to have allowed him to take the medication and get a paramedic to attend. Further reading suggests it was a heart attack, if he had medication it would have been a known condition however given the panic caused he might not have been in the right mindset to tell the police that.
To conclude, whilst more information would be useful in making a good judgement, the police were wrong to drag the parents away from their dying daughter, and to prevent the father from getting medication which could be life saving, they could have done more to calm the situation, they started off well but it didn't help them crowding around the parents with 4 police officers and 2 security guards, it might have been better to have a couple approach and talk to the parents whilst the other 4 police/security wait in the background. The parents could have been more reasonable though and had a more reasonable conversation and also perhaps the hospital staff were wrong also. 30 minutes prior to that they were told the life support was to be switched off, pushing a doctor cannot be tolerated and hospitals do have a panic number to dial for emergency paramedics, heart conditions and security. The police could have asked about the doctor being pushed and the parents might have said they were sorry for that but it was in the heat of the moment as they didn't want their daughter to die.