Is there even a legal basis to sue over? Did OP have a contract stipulating they'd be offered a return plane ticket?

@Magisch IANAL, but this comes to mind: en.wikipedia.org/wiki/Estoppel#Promissory_estoppel_2

@Magisch I don't know, which is why I suggest a lawyer. By a stretch of the imagination it's kidnapping & false imprisonment (in the airport). That sounds very drastic, which is why he needs a lawyer. Back from my days of studying law, a few decades back & probably in a different country, the phrase "reasonable expectation" came up a lot. And I think he had mo0re than a reasonable expectation of a return flight, which might be presumed a contract “I fly there & talk to you, and you play for it, including returning me home”. But, I never completed my law degree & the OP needs real legal advice

@Magisch it depends on the jurisdiction. E.g. in Germany an employer is required to recompense travel-costs for interviews unless they announced they would not do it in advance.

Agreed (+1). OP, can you please add a country tag? Thanks.

@mawg He mentioned Greyhound buses in his post, so I'm fairly certain this is USA.

Or, by Googling Greyhound bus, he might be in the UK, Australia, Canada or South Africa. OP, can you please add a country tag? Thanks

@Magisch: I'd even go as far to say that there is a contract. When the company invited him for an interview and agreed to pay flight and lodging, they basically said: "We will pay you a flight to X and back and an hotel at X. In exchange you will come to our office, conduct interviews with us, and let us evaluate you as a possible employee." So maybe you don't even need to resort to "promissory estoppel".

@Mawg Greyhound buses are uncommon in the UK (I've lived here all my life and didn't know we had them). If the OP were in the UK, I'd have expected he'd have taken a Megabus, a train, or a National Express coach.

You say "GlassDoor, etc", but I think that this is extreme enough that the local press may be interested in the story, and would make a good addition to that list.

Why didn't I think of this? Of course, the OP has to be careful how he words it and let himself be drawn into expressing opinions which might seem libellous in print. Maybe ask his lawyer’s advice? Possibly a lawyer suggesting that might be enough to lead to some compensation.

@Tim Flights from London to Glasgow or N.I for instance? But, why do we waste our time second guessing each other? OP, please post a location. Vlaz that's an excellent point.

@Mawg thanks. And also think a country tag is needed. It seems quite likely to be the USA but then again - it might not be. And it's hard to give a good advice on a maybe fact.

Agreed, but IMO the only real advice the OP needs is to get lawyered up

@Mawg as the most minor of notes, your footnote starts "IANA" so we aren't certain what you're not.

I am an attorney, but this is not legal advice... But both contract and promissory estoppel theories seem like they'd help OP here. Also -- and again, this is not legal advice -- you can't really be sued for stating your opinion. Defamation suits require false statements. So do false light suits and most other speech-related causes of action. There might be some state laws that make true statements of opinion illegal, but as long as OP doesn't breach an NDA and doesn't lie, he should be fine.

@Snah lookup some higher manager and boss at that company and throw them a mail explaining the situation. Maybe helps. Because that could have been a single persons decision.