Media availability for Leaman is really interesting, worth a listen if you want to know more. I forgot that McCoy was also on that Peterborough championship team so he definitely has someone he's familiar with on the team.
tl;dw- He talks through a lot of the thought process of bringing him in, a bit of his own opinions on the rules (and why that ultimately doesn't matter), and the rapid turnaround Simpson had to go through to get there (Savannah->LaGuardia->Montreal, get F1 visa->LaGuardia ft customs->Providence). He arrived on campus 9:30 pm Saturday after the game. Then he had to get paperwork done, enroll in classes, physical, heart exam, etc. Seems he's finally getting on the ice.
Basically: if one of their goalies is sick or injured for the rest of the year, they would have had to forfeit the game. He had gone the club goalie route in the past but after he felt bad for ruining their club eligibility, even if they had been willing. They asked a few junior kids but they didn't want to leave their teams mid-season, and he wasn't going to push them if they weren't willing. Even if he isn't a fan of the rules, they are there and teams must adapt.
I like the news of them getting Simpson as backup for Parsons at this time. Considering Michigan's #1 just got hurt, too, over the weekend, good timing for PC to add a goalie before he could've been scooped up elsewhere.
Leaman also addresses this- Michigan can't add someone anyways since their classes have already began. But totally possible other schools were looking around. We know of at least one defenseman coming in at winter who flipped from NMU to CC when they lost Beckner for the season. NMU got someone from juniors instead.
Basically Providence is really really really lucky that the injury happened right at this time.