Why is everybody so convinced it doesn't make sense and we are being lied to? There is a link in an earlier post on this thread (buttermilkwaffles at 14:56) to a tweet which contains informatoin from an A&E consultant in Manchester. He says that normally, when a patient of the PM's age arrives, they would be put on oxygen and check oxygenation levels. If their oxygenation level is going up and down they lie the patient on their stomach. If that doesn't help they transfer the patient to intensive care and continue to observe their oxygen levels. If oxygenation drops below 88% they move to PCAP (giving oxygen with pressure). If that doesn't work the next step is a ventilator.
As this is the PM we are dealing with they may well have transferred him to intensive care earlier than other patients. But there is nothing inconsistent about a patient with this virus being in intensive care and in good spirits. All it means is that his oxygen level isn't stabilising.
It may be that he is in a worse condition than we've been told but everything that has been said so far is entirely consistent with the way this virus behaves and the way it is treated as far as I can see.