My main point wasn't that Usagi was meant to come out victorious (even though that's true, let's face it), but it would be unrealistic to ignore what the writers would have done with three less sailor senshi, and I've noted what they have to work with and why they still would have been enough for the good guys to pull through.
For instance, it makes no sense to assume that Venus would still wait to appear at the same time, when the circumstances would clearly be different. It would also be wrong to assume that every monster, scheme and encounter will repeat itself along a timeline that no longer exists. (And those assumptions are not suggested by the topic's subject or their opening post, unless you know SailorStar9 well enough to see through the mistake that they had made in the conveyance of their question, which looks open-ended to me.) For all we know, there wouldn't be 40-46 episodes in the first season, there might not be as many youma/schemes to deal with, and whichever ones that happen to be used might not occur in the same order. Heck, maybe being alone and having to rely more on herself for a longer period of time might actually help Usagi to get her shit together. In the end, though, all any one of us can do is guess about those things.
As for Usagi dealing with the "cops" in the airport, that would depend on whether it still happens, and how she has developed by herself by whatever time it takes place. If she's more competent, which is where I would expect the writers to take things, she'll be sure to deal with them somehow. Even if that's not the case, and she's little different from the canon where she has two teammates, if it turns out to be hopeless she's always got that "wail of doom" thing, which I'll assume can take care of/incapacitate small fry (even if they're mud golems) long enough for an escape, unless it actually manages to defeat them.