Similar to my thought I was about to post Alsdarana.

Yea, can't fully prevent the free rides from boosted AoTCs without strict requirements, which aren't typical for AoTC groups and they might ignore and apply anyways.

Two thought come to mind to help keep them out of the community:
1) The requirement to submit a log on a single target boss fight, meeting x% of their max dps based off a screenshot of a raidbots sim they provided, to get a community invite.
2) Allow leaders to leave public feedback for raiders that didn't meet stated guidelines that are reasonable to be expected at a heroic raiding level, using other guidelines to remove such people from the community.

Such as: X dps or effective healing was stated to be a requirement but they came in with dps lower than tanks to the point it significantly hindered our group on a boss we didn't kill.
or the higher end like: claimed to understand and handle bomb popping duty on Painsmith without popping 2 bombs before the debuff dropped or popping a bomb when healthbars we're too low but wiped the raid doing so twice.

Likewise, allow attendees to leave mod veted public feedback for leaders restricted to things like: "claimed to know all fights and mechanics and would assig duties to wipe-causing mechanics but didn't address x mechanic which caused a wipe," among other things.