Demo flights can be... also fun...
Distracting is an all encompassing word... distracting from what?. The plane's captain was an experienced test pilot, used to regimen in order to accomplish his tasks. As a lifelong military pilot I can appreciate how the captain felt to 'get away' from the daily regimen of test flying. IMHO he got way too loose, disregarded basic safety, flight planning and even crew coordination, if the reports in Russian media can be believed.
I would not pretend to know how to demonstrate a civilian airliner, but even a tactical military transport, with PAX aboard, should be treated more like an airliner.