The fact that DVDprofiler is custom software in itself probably makes things harder to update the backend for, as all it takes is for one of the supporting bits of software to have had a change in how it behaves under X condition for it to potentially cause an issue that'll need to be fixed.
And if this is the only place using that specific bit of code, you don't necessarily know about the issue until you've moved to the new hardware/os.

I've been on a few forums that are now in their 20th+ year and have had relatively minor customisation, often by the one guy and it's surprising how many times a change that was made 10+ years ago tends to be forgotten and cause an issue* (I hate to say it, a lot of programmers don't keep great notes for "minor" changes), and the DVD profiler system is a lot more complicated with far more records in it's DB's than most forums.

If the old hardware for this site was failing faster than planned there is a good chance that there wasn't time to do massively extensive prep.

I'm guessing Ken probably has a day job so may be limited in how much time he can spend sorting it out, and depending on what needs to be done it may require a fair bit of tracking down and double checking.
Bare in mind that the DB transfer/getting the basic site up took something like 2 days, so I doubt he's going to be in any rush to make any changes that might possibly require doing something like reimporting/rebuilding a DB, and potentially it's could take a hours/days for any change he tries on a test system to be ready.


*One had an entirely separate DB the dev forgot about for one of the add ons he'd written, it was only spotted (despite testing) when all the old hardware was turned off as the new install still referred to the original server for that one set of files.