Why may AAP govt. in Delhi be termed as opportunistic?

Today Mr. Arvind Kejriwal took oath as the youngest CM of city state Delhi along with his 6 colleagues, thus forming first non-Congress and non-BJP, and first govt. of "AAM ADAMI", as termed by Mr. Kejriwal. Formation of AAP govt. in Delhi has been closely followed, debated and discussed not only in media, but in general public also. There is no doubt that AAP and Kejriwal have given rise to a new hope to common men that he/she also has a place in the political system of this country, he/she can also be the agent of change, and we can expect for a clean and good administration. But, this is to be noted that AAP has formed this govt. with outside support of Congress. This situation gives rise to certain questions. It can be asked - What kind of politics it is:  opportunistic or practical?

साध्य के साथ साथ साधन का भी पवित्र होना जरूरी होता है शायद, लेकिन राजनीति में सब जायज है| I know that they have all reasons to justify their decision - but any pact or coordination or alliance with Congress or BJP should be a strict no-no. Mr. Prashant Bhushan has said that sticking to a ideology narrows support base, while raising popular issues widens it. (Read http://timesofindia.indiatimes.com/assembly-elections-2013/delhi-assembly-elections/aap-congress-tie-up-undemocratic-prashant-bhushan/articleshow/27764897.cms). This can be true in short-term, but an ideology is required to stay relevant in long term. So, what is the target of AAP? They have promised an alternative politics, but if govt. with Congress support is the end result, then God save us from this kind of politics. Once that moral high ground is lost, then you are no longer different from other parties that are already part of political spectrum. You are just another party following same principle - Say one thing, Do other thing. Every thing can not be fair just in the name of so called "People's will". Remember, sometimes this will can be very nasty, so what we will do then? - fulfil it. In democracy, people's will is most important, but it can not be supreme in all situations. That's why institutions are raised and nurtured leading to a healthy and participative democracy. In India, this has been achieved to some extent. But, our political system and establishment has all these years compromised it for their advantage leading to wide spread corruption, opportunism etc. It seems AAP is also going to be the part of this dirty game. Best of luck AAP! Best of luck Mr. Kejriwal! Hope you are the true agent of change.