Obviously I cannot run Stockfish at similar configurations, because I don't own a 64-core cluster, but it doesn't matter if the same depth is reached by a cheaper configuration in the end. If the match-version uses 1 minute on each move, a normal PC should reach similar depth in a couple of hours, maybe overnight. I am not claiming that this is perfect, but it's a start.
Even if it is possible to reproduce these games, there is still the >0 chance that the games were manufactured beforehand. It is common knowledge in correspondence chess that an engine operated by a strong human player will beat a naked engine easily. This is actually what playing strength in correspondence chess is all about. Since the team has access to Stockfish, which is open source after all, it can construct a database of wins that can be reproduced. There was a "professor" from the Ukraine who won a blindfold(!) match against Rybka a couple of years ago, obviously by memorizing wins. Google it if you don't believe me.
Don't forget that this match didn't have a set date. Unless this stuff is run real time with brand new version of Stockfish and complete logs of every action, it can be faked and it is not even difficult. If there are millions of dollars at stake on the stockmarket, it can even be an expensive fake.
I remember the Kasparov vs. Deep Blue match, where Kasparov claimed that he got cheated and wanted to see the logs. Since Deep Blue got dismantled after the match, at least that evidence got lost.
I can't say much about AlphaGo, but I am pretty sure that it is possible to pay a top player to lose in a less than trivial way. It has happened many times in all sorts of sports. Also Go is not as researched as chess, so it is not clear how strong the strongest humans really are. Maybe they are as good as chessplayers were 400 years ago. Those guys would lose to chess engines from the 90s, so maybe AlphaGo is good but not exceptional in any way.
There are lots of open questions and they all have something to do with integrity. If there is one thing that we have learned over the last decade, it is that integrity and the Yeti have a lot in common.