Not even remotely true. BU's record vs. Collins is 11-5. If you take out those two first seasons where BU was building things up, it looks even better at 11-3.
Why wouldn't I? First, more success at every single coaching stop he's had. Second, since you love the head-to-head, he has a .688 winning percentage against him. And then, Collins has also had momentum before and failed to capitalize. At one point he had two straight 20-win seasons in 2016-17 and 2017-18, making the tournament in the latter. That's a program on the rise you can sell to recruits, right? How did he build on that? With 5 straight losing seasons. Then he finally turned things around again, making the tournament 2 straight years and then...16-15.
He's a fine coach for what that job is, but there's a reason major programs aren't banging down his door. I'm not even saying the reason is that he's bad. The reason is that he hasn't really shown anything. He's worked at one of the few high-major programs where losing is actually OK, and the where you can be celebrated for simply not losing sometimes. If you want to hire a guy who is going to win, you just don't know if he gives you that, and you also gotta wonder why he's stuck with Northwestern for so long and hasn't tried to go somewhere that actually cares about winning championships.