TJ.
I'd have thought that it was obvious, he probably has a pretty good idea of what percentage of the voting population would be able to provide your level of analysis ( I, for one, would not) and what percentage of the population would be more likely to elect him based on what he's said.
He – like all mainstream politicians – has done the maths and will act accordingly. Most of them probably believe that a little blurring of the reality is justifiable as they will save the country form the terrible mess that their opponents will create.
To a large extent, we get the politicians we deserve. Imagine a politician saying something like:-
"well the evidence suggests that to make thing x happen we should do thing y – but hey we can't be 100% sure, we're just doing what we think is best for the country" – instant savaging by the press / opposition.
I'm even sure that many politicians start out wanting to be accurate and honest but soon realise that spin and messaging is the only way in the current system to achieve any of their aspirations to change things for the better.
Gosh, a long post, sorry.