I do not think there is anything wrong with being polite as long as Truth is not sacrificed for politeness.
And as I do believe, this article and/or what I posted above clearly shows how, even if one does not wish to be Catholic, you aren’t going to offend God if you call a priest “father”.
As with many practical Truths in scripture, it all depends on what is known. Certainly, someone ignorant of scripture and Christian principles will not be called to account by violating such a specific command to "call no man on earth father," but those cognizant of such an admonition are committing a sin of doubtfulness if they violate their consciences, no matter what YOU may think of the issue.
The article doesn't show any such thing...If it did, there would be multitudes of millions of non Catholic Christians agreeing with you...And they aren't...
God may not be offended, but it's going to tick him off...I won't call any spiritual leader Father...Anytime, anywhere...