I've spent a little time the past two days researching possible answers to both questions and I think that the answer here has to do with answer-ability.
https://sports.stackexchange.com/questions/2417/what-is-the-lowest-bowling-score-under-a-recorded-average#question is incredibly hard to answer, if not outright impossible. I went through tens of websites through Google trying to figure out how to even word this question to find any information on bowling below averages. Some of the obstacles I continuously ran into when dealing with bowling data:
Bowling records don't focus on negatives. Conventionally, these records focus on high performance results, like 300 points games and most consecutive frames with a mark. They do not focus on things like most consecutive frames without a mark. Bowling scores below averages falls into the negative record category.
Bowling records are very regional and not universally organized. While records like most consecutive strikes may be easy to find because it gets plastered everywhere (here, here, and here), other records are going to be recorded by the organization that bowler belongs to and not easily disseminated or combined with all bowling records. This leads to issue #3:
There are a lot of bowling tournaments spread out across a lot of bowling organizations. Take a look at this section of the Ten-Pin Bowling Wikipedia page. It notes:
Around the world, there are numerous local, regional and national tournaments held, normally with the only basic requirement that a bowler be a certified member of a national bowling organization.
There are a massive amount of bowling organizations and tournaments to begin with. And if you throw in league play, you're looking at millions of games a year being played by an uncountably large number of bowlers.
Beyond the difficulty in bowling data, I find it a little difficult to even know where to start with the question. The OP mentions that he saw this in a tournament, but doesn't specify if he would like the answer to only address tournament play. Do I look through all the records for league games?
This question could also come up with a lot of answers that aren't supported by data. Answer A says they saw a player go 165 pins under average once. Answer B says they personally bowled 167 under. We don't even have a source from the OP, so we couldn't compare their situation with other situations in the same organization. The sourcing for answers to this question would just be a mess.
The upside is that a answer would only have to find one example that showed his example wasn't a record to say "No, 150 pins below average is not a record because it was more in this one instance." In retrospect, this question probably shouldn't have been closed as "too localized," but it probably should have been closed as "not a real question" and suggestions on how to edit it to reduce the scope should have been made in the comments.
Dealing with Lowest average to bowl a 300 game?, we run into a lot of the same data issues as the first. What constitutes a "sanctioned average?" Where do I even start looking, and how do I know I have found the answer when there are so many bowlers out there? Sure, USA Today in 2002 might have had an answer, but is that really up to date?
In fact, to a large extent I see this question as being more problematic as the first. At least with the first question an answer would only have to cite one example; with this question, you could end up with far more information and incorrect answers because it requires looking until all 300 game scores have been evaluated. This question also could have been closed, probably for the same reason as above.
The sport of ten-pin bowling is played by such a large amount of people across such a large number of organizations across the world that it's hard to find appropriate answers for more obscure records. This isn't a fault of either question, but an issue with the scope of bowling in general. If the original questions reduced their scope to only look at a certain time period or organization, that would make accurately answering them more probable. Problematically, this may also lead them to be closed for being "too localized." The questions
In the USBC, what is the lowest score under a bowler's average on record?
In the PBA, what is the lowest average for a bowler that scored a 300 pin game?
are going to be much more answerable than the current question. But they are pretty localized.
So to answer your question, I don't think that either of these questions are really in scope because they deal with such broad topics, but to make them more localized may actually cause them to be "too localized."