I think any philosophical uniqueness in Aikido comes from the predetermined position of maintaining one's mental and spiritual (and physical if things get to that point)centre to be able to extend love and preserve the aggressor even in the face of extreme danger and death, through the realisation that "there is no enemy".
This is what, if anything makes it a bit different from other styles. I don't think that an Aikidoka that employs the philosophy should ever allow him/herself get to the point where any technique is executed out of fear or desperation, thereby engendering the need to damage or injure the other person for the sake of self preservation.
The challenge in this though is to become so highly skilled in all aspects of the way and the science that the ability to defend oneself without needing or wanting to injure the other person is achieved on all levels.
I think this philosophy extends to and is especially developed in Aikido competition in its modern sense (shiai, not shinken shobu). In paired kata practice and cooperative randorigeiko one does not always come across the willful denial and the serious and purposeful challenge of one's ego by another through the vehicle of skilled resistance.
It is very easy to be all harmonious when no one is really testing you and pushing you all the way and seriously trying to defeat you. Some say that the sports arena is the modern day version of the battlefield, I don't agree completely, but I think that if one can truly compete (i.e. shiai - to meet and to test) and maintain that centre under extreme pressure and still preserve harmony with the other person (i.e. not become emotional and want to destroy or damage the other because they are losing), then that person just might have a deeper understanding of just what it takes to really walk the path of harmony, than one who does not have their comfort zone seriously challenged on a regular basis.
So I think that the philosophy of Aikido does allow for competition and it is an important part of the training, as this element places a degree of pressure on the person to perform at his/her best while maintaining the tenets of mutual harmony. On top of this, there is even more pressure not to become so caught up in the challenge and pomp of victory and ego gratification, such that in the end centre is lost and malice for the other person enters. The beauty of competition and harmony of conflict is that even when one "loses", he wins by understanding the weaknesses of his technique and self and thereby forges onward to improve himself.
We have a saying here "You never know yourself until your back's against the wall." Too often have I seen Aikidoka (including myself) who simply collapse under the pressure of extreme and severe resistance, resorting to more primitive survival-based responses and training systems in the face of danger - this is what we strive to reprogram in Aikido, to get to the point where even under extreme difficulty we do not lose the direction of our higher selves and resort to animal behaviour.
Apologies for the length of the post.