Any interim manager we appoint is taking on a very limited role. No real time to properly bed in a new system, unlikely to have much influence over what we do in the transfer window, already in a bad position in the league.
To my mind all the interim manager can really do is get the players he has on board, engender good spirit and morale about the club again, set up the team in a coherent way and see what happens. Given Solkjaer's status at the club and general demeanour, I can't think of anyone we were likely to get who would be more suited to engendering that morale and good spirit at amongst the players, fans and club generally. People have suggested that Mourinho's sour personality, abrasive man management style and constant criticism of the players has played a large part in their underperformances. Well Solskjaer is the antithesis of that.
Normally that wouldn't be enough to make a manager a good appointment but given the circumstances and the narrow timeframe he's operating in it may be enough the resuscitate the team for the remainder of the season at least. He would never be a contender for the role full time in my eyes but these are special circumstances.