I see where you're going with this. I normally would agree. In this case, we have a large, C program that evolved over time for a complicated feature set. That they trimmed that much fat out might already be saying something about how much risk might be in that code. It's also been around a long time in important infrastructure plus will continue to be. Converting it to something that's safer in most ways, esp dynamic memory & types, to reduce number of vulnerabilities in near and long-term makes sense.

So long as one can convert it in a straight-forward way that preserves the current meaning of the program's statements. If not, the port might introduce new problems.

Edit: Btw, send me an email (see profile). Got something you might be interested in. One or two things.