"I assume the owner is now just the gentleman..."
I would certainly not assume that. In fact, he most likely isn't, otherwise that would defeat the purpose of doing this.
As you say, it does sound as though this has been done to limit care home fees.
In this situation, as a pp said, the old gentleman will only own 50% (or any other percentage that might be written down somewhere) and the other 50% is held on trust for whoever is named in the will of the wife who died.
In reality, the owners of the house are both the old gentleman and the trust fund that holds the 50% of the house from the deceased wife.
Where a house is owned as tenants in common then a person can sell their share of the house to someone else. In this situation, if you are just buying from the old gentleman then you are just buying his 50% of the house, you are not buying the other 50%.
Whoever is the trustee of the trust holding the other 50% has to also agree to sell the house.
It may well be that it is the trustee of the trust who is arranging this sale now that this person has gone into care, but they need to sell you their 50% as well as the old gentleman selling you his 50%.