Yes, I can see your position, but I will not take your advice to refrain from making offers with particular terms in them. 

IMO there is no evidence either in this thread, or in the make-an-offer ebay policy that identifies that I have breached any ebay rules. I also do not see that I am making a "demand" - my terms are a proposal to seller that is time limited. A seller can decline, or counter-offer, or accept or do nothing, they have a range of choices.

My position on this matter is not theoretical, it is based on a number of successful transactions through make an offer that have included clear terms pertaining to my offer. 

Nothwithstanding, I have had sellers decline my offers, and others that did not respond in any way, I have yet to strike a seller who has explicitly advised me that they have got any issue with my terms nor one that has accepted an offer, after terms regarding timeline for my offer have passed. 

Except for a small number on these boards, I generally find the vast majority of sellers I deal with very open-minded to getting a sale.