Nor stryke nor the moderator is an idiot. Stryke is only providing incomplete information and the other is more less pointing that out with his 'according to'.
In fact it really depends on the country or even the series you race. When you are racing different series in different countries it might even become confusing what to bring (especially regarding the 'dress code')... With a forum with even more nationalities it becomes even much more confusing, especially when statements are made perhaps completely valid for country A but not applicable for country (or series) B.
Just two examples for neighbouring countries: - For the German MDC and SDC-series you have to run two working brakes ("Zwei Bremsen sind Pflicht"), full face, basically body protector, knee protection, etc... Some single events used totally different rules however.
- The Dutch D4XS-series you could start last year in a T-shirt with DJ-helmet or on a SS with one brake or combining both...
So, it depends on the series / sanctioning body if you want to race. Go to the website of the organiser and have a look at their rules...
Especially when the serie includes BMX tracks or BMX-type tracks on a surface without any serious slope, they will probably try to rule out BMX bikes from entering a 4X event; the same applies (here) for tyring to rule out the use of CX bikes for XC events. To do so, all kind of creative rules are made for tire size, use of front brakes, gearing or even suspension.
If the track design/choice was good in the first place this would not be necessary, since these other bikes would rule out themselves due to not being suitable instead of an advantage. Based on the availibility of accommodations sometimes compromises are needed however. Just my $0.02
For just having fun on a 4X track it is not very interesting anyway. Yes, you can run that bike for sure; although depending on the course and your intention you might appreciate the huge increase in stopping power with a front brake as well as the advantage of gears.