I had the exact same doubts, coming from different experiences and practices.
It’s still part of the ‘propaganda’ that angels and demons are enemies. By working with the DOM book you are not calling the angels with the intent to subjugate the demons, but rather to help you having the right power to call a demon to make your request, more like facilitator or, as DarkestKnight put it, framework.
It is true that at the beginning of the book it states that the angels will bind or force the demon to work (or something along those lines) but I didn’t have that feeling when doing the rituals, and also it’s a matter of how you use the ritual. If you are having the intention of forcibly make the demons to do your bidding thanks to the mighty power of god and angels, yeah you may be antagonising the demons if you are into that kind of vision.
If instead, you are tapping to the power of angels and demon to have the strength to ask, firmly but with respect, the demon to do something for you, I don’t think you are antagonising those entities more than a good leader is antagonising his team when asking to work on a project and deliver the expected results.
It’s a matter of having the authority to ask for something and, even if you are using the power of angels to do it, it is in your right to do so but again, there’s a difference on how power is wielded.
Also, the demons are still the raw and chaotic force of the existence, according to Qabalah, so I’m guessing in this case the angels serve more as a direction to firmly steer the demon in the right direction without disperding his energies, kind of like creating a furrow to make a river flow easily in the right direction after a dam is open, as angels represent the more stable and constructive side of the existence (I’m still taking concepts from the tree of life / tree of knowledge of Qabalah and my own personal vision, which may differ from someone else’s).
I have done a couple of rituals from the book in the last couple of weeks and I am yet to see the results, but it seems that a lot of people are having success with it so I guess that at the end of the day you have to ask to yourself if you want to just enjoy the idea of having demons as “friends” or if you want results and shape your existence to be happy.
You can find my posts about this in this topic, which I advise to read because I’ve been given some good advice there that helped me overcome my doubts about working with this book: Whats the difference in how different “love” demons work? - #50 by Norski