There are three ways that the age of stone artifacts are estimated.
1. The design and craftsmanship used in the artifact, along with the type of stone used and its source. This will often place it within a certain era when such techniques and sources were commonly used. Just because the size of the axe was "unique" doesn't mean that it does not show signs of workmanship and design that correspond to other tools.
2. The positon of the stone tool in sediments, the depth of burial, can give an indication of when the tool was dropped, lost, or abandoned. It is not clear in this case if this teqnique was used to determine the age.
3. Radio carbon dating of associated fire or plant materials can give an indecation of when the artifact was left at the site. This does not appear to have been done in this case.
It is misleading to say that Ian Leitch is being deceptive by using "weasel language and disclaimers". By saying "probably" and by using disclaimers, he is exactly admitting the difficulties in dating the stone axe. There is no reason to believe that the axe was of recent origin, and he is giving his opinion and the reasons for it. I don't see any deception there. In fact, he is doing exactly the opposite of deception. He is being as precise as possible.
Being that the post-flood age of the earth is five thousand years, then are we talking about precision that can be off by 100%? That's honesty?