excuse or not

Is there such a thing as giving an excuse for not making a drastic decision?

It would depend very much upon how life changing such a decision would result in.
If it's a matter of not wanting to decide on a place to have lunch, then it's probably an excuse - we could have chosen not to volunteer a place out of politeness or consideration for another person's preferences.
If it's a matter which will affect another person, then I think taking time to consider and re-consider before actually deciding, is not making an excuse.

I have always recited this mantra that if a hand is bad, chop it off.
If a person is everything bad, then walk away - I don't believe in second chances because after time on this earth, a person's selfish state will become his underlying trait. Practice makes perfect - so when you are constantly selfish, it eventually ingrains itself into the personality make-up.

I have been in this state of limbo, for a very long time - more than 4 years - of deciding.
The reason I have been so delayed in executing this decision is because the ripple effect is going to be enormous - almost close to a tsunami. So, it's not that I have not made a decision - I have simply delayed the execution verbally, but on the technicalities, it's been done.

So, although we seem to be giving an excuse - we may actually not be doing that at all.
If there is one thing I have learnt in my life, is to be diplomatic and professional - but the end result is the same - it's just that I prefer a less confronting delivery.

Therefore, sometimes when we think a person is giving an excuse, we should think about whether it is really an excuse or just buying of time before it is verbalised.