I think this would be great if it were provided to HCP's in training or in their clinical settings; I wouldn't personally like to hand it over to a midwife, especially in a hospital birth setting where I was pretty much guaranteed to have never met her before!
However, I understand that while the post seems "precious", it sets a good message. it seems frivolous because this language has been used for so long, but the positive language is less about semantics of words to me, and more about attitude toward the labouring lady. For example, it is far too common for HCP's in this country to do things in labour without either explaining why they think it would be helpful, or sometimes even doing things without any prior warning. Also agree with the language directed at trusting the mum a bit more, I think this happens a lot and certainly to me; MW assumed I couldn't possibly know what I was talking about when I was grunting with the effort of pushing DD out right then and there and insisted she would come and check on me in "about four hours to see if I was ready to push" 
When you are in pain and out of your depth really many of the the last things you need are unfortunately pretty common practice in hospital births. So while I agree giving a poster of "acceptable phrases" to someone I had just met seems overstepping the line, it's useful for women to see posters like this, that portray a more positive birth experience, that they can use to for example build a birth plan and lay down their preferences at the start of labour.
I had no idea I could request or question anything the midwife suggested and I had a really bad time solely because of my perceived treatment by her, and this time I plan to go in being clear of m own preferences and limits; in practice though this is hard, especially the first time round, and it would be nice if it didn't feel like such a hard learned lesson.
I, like most women I'm sure, just want to be treated with respect and compassion in what is a fucking difficult, painful, undignified time for many.