...it's a common occurrence at clubs here in France - well, tow bar plus prop, mostly.
Yes, I should have made that clearer: we were using a tow bar, as well as pushing on the prop.
...a reasonable safety argument...[..]...By holding the prop at the root you will not only minimize stress on the bearings, blades etc you will also have far less risk of turning the prop.
That sounds logical, I like it.