Using Navarro as DH against RHP will eliminate some (or most) of the good in trading Lind, but if they are actually smart and strictly use Edwin in that role while keeping the DH spot occasionally free to rest key players throughout the season, then they did the right thing (trading Lind) and it's not even debatable. How many teams have strict DH's? Not many. It's a position that is and should be used to rotate players around and give guys a breather over the course of a season. If you have a David Ortiz type, then that's when you have a strict DH. The Jays happen to have one in Edwin, so there was no point in having another in Lind that has chronic injury issues, can't play defense, and is useless against one side of the plate. At least with Smoak he will provide defensive value with some HR power and the ability to draw walks for 6m less.
The Jays will miss Lind's bat against rhp, no question about that, but as far as money saved, roster construction, and making the most out of the DH position, they had to trade Lind. If the team decides to use Navarro at DH against rhp, then that doesn't make the Lind trade any less sensible. It just means they are clueless about how bad Navarro really is.