Well yeah. In my full post, not the selection you quoted, I believe I touched on that:

"You have nothing to worry about so long as you're taking the bump in good faith -- you are intending to fly when you approach the interaction, you fly the flight if you're not needed, and you ultimately fly the backup flight if you are bumped."

I remember reading, here?, a story about this activity leading to legal action when the ticket buyer was an insider � I think a ramp employee in the Pacific Northwest who had access to load info and knew which refundable tickets to buy.

i was on a mileage ticket that i really didn't want to do...got bumped on the outbound and just cancelled it. called my friend and just said flight trouble can't make it this weekend.

i hope UA doesn't consider that fraud. granted this was a year ago.

Not sure what the morality of taking bump vouchers has to do with OP; it appears that they are asking if taking them is against United's rules and regulations, not what John Doe thinks of airlines banning people from their FF programs and what criteria justifies one's banning from an airline.

Anyhow, the Rolling Stone article details that "Lucky" was attempting to gather as many vouchers as possible, often in questionable methods -- submitting large amounts of bogus complaints, exploiting computer security holes, etc. then proceeded to brag about it far and wide about how "The people running the airlines are all a bunch of idiots" -- the same "idiots" who revoked all of his vouchers and banned "Lucky" from MileagePlus.

-LPDAL

Taking bumps is not against UAL policy or rules. And yes there is a possibility of being banned from UAL if you take bumps. If you are acting in good faith and the airline correctly assesses the situation, then this risk is rather remote.