The article doesn't add anything new to the discussion. It tries to make a straight business deal into an emotional issue due to the back story on the IT trade. DA typically made a calculated decision once Kyrie became available. A decision to improve the Celtics.
The idea of loyalty in sport, and the NBA in particular, went missing a long time ago. It probably declined in an inverse ratio to the amount of money involved. No stories about loyalty came out about the AB move to Detroit. As much as IT did in his two years, AB was at least equally deserving of loyalty.
The way the wage structure is in the NBA and the cap make loyalty a difficult thing to show. AB deserved his pay day, DA (a long time supporter of AB) decided he couldn't afford AB and improve the team in the ways he needed. In the present NBA you need a number of players at a level AB isn't quite at. While the Celtics are top of the East we all accept that they will struggle to beat a number of teams they will meet on the way to a championship. DA had to improve the team and may still do dependent on what happens with Hayward (and other things).
I don't see much difference between what DA did with AB and IT, just that they developed differently. A player with the Celtics history of Pierce understood his move to the Nets was a business decision (a very good one as it has turned out). Anyone in DA's position who lets sentimentality get in the way of a decision that gains you a player like Kyrie and gets you closer to being a contender should quit.
The IT trade doesn't show loyalty but lets not pretend it is a new low or any different to lots of other moves just because IT was upset.