My son can’t handle money

My answer would be no.
Firstly, it's not fair on your daughters. I'd be fuming if I were them.
You say your son constantly has his hand out for help with debts, so even if you gave him the deposit money to buy a house do you honestly think he is capable of paying a mortgage for the next 25 years. Of course not. He would be holding his hand out to you to pay it.
He has a roof over his head already. Like the rest of us, we can't always have what we want.

As regards the house, have you thought of buying a place for him to live in and getting him to pay rent. If you will be paying the deposit you might also be able to get a mortgage.
I realise that this isn't a good idea for everyone, but I'm only making the suggestion because that is what we did for our eldest son when we thought he couldn't be trusted with anymore handouts - very long story. And it's worked very well, got DS back on his feet and meant that the rent money he would have to pay in any case actually stayed within the family.
You don't mention how old your DS is but in my experience all youngsters need support until they are at least 30 these days. By that age they will hopefully be able to support themselves at least financially. Emotional support is, I'm afraid, a lifetime commitment on our part.

Maybe your help in assisting him to set up a help-to-buy ISA and encourage him to save on a regular basis rather than any financial contribution yourselves.
Help him to research the options available at present so that he can start to take responsibility for himself.
In the long run this could be the start to "enabling" him?