Slippery slope is only a fallacy when there's little to no evidence that you'll fall down the slope. When there is evidence or logic showing that it truly is slippery, it's not a fallacy anymore. Even from the article you linked:

> The strength of such an argument depends on whether the small step really is likely to lead to the effect

Some would say it is very likely for power-tripping HOA members to continue sliding down the slope.