I think he's earned the chance. To not give him a chance to build on the past couple of months would show an extreme confidence/arrogance in their ability to find someone better that this ownership group has not earned yet.
I don't quite buy into the 'this is the most important decision in years' talk about this appointment. Meh. I think there needs to be less hysteria in general about the singular importance of the Head Coach. In 90% of clubs it's a revolving door position. If Sheehan doesn't work out, we'll bin him off and find someone else. If he does work out, he'll get poached and we'll be looking for someone else anyway. Let's focus on stability in the areas we have more long-term control over like recruitment and youth development and be a club that is well-run enough to not think the world is collapsing if we have to go through a few Head Coaches along the way.
In many ways, Montague and his ability to assemble a squad that 'overperforms the budget' is more important to our future success than Alan Sheehan. Sheehan showed that just casting off the 'swansea way' ideological horsesh*t and ramping up the energy levels was enough to get us performing well enough in this league. It's Monty's task to get a matchday squad together that can build on that and sustain that over a full season.
In a recent interview Sheehan mentioned he believes the style of play he wants to use is one that will allow us to overperform in this league and that he'd discussed that with Monty. Now, that could just be Sheehan pandering to his bosses favourite term, but the mindset aligns - rather than how do we get these players to play the 'swansea way', it's how to we play that makes them more than the sum of their parts? It's a much healthier place to be in my opinion, but of course, it could all just be unsustainable and we'll flounder, but I'd much rather be in this pragmatic post-process manager phase than still stuck where we were, and it's worked a treat so far.