Why go through the expense of purchasing an airline just to capture the pilots when they can simply interview and hire the ones they want?

While I tend to agree it won’t happen, I’m not certain. Why are you certain?

Why would they bother buying anyone for pilots when they can pick and choose who they want to hire?

1. There are reasons some regional lifers are regional lifers.
2. They would rather hire ex-military, especially retired ex military, who due to their age will have a lower average wage over the course of their remaining career, already have a pension with offset for inflation, TRICARE for medical coverage, little experience with union negotiating, and have a 20 year history of conformity to the norms of an organization.
3. Their existing pilots would demand expensive concessions on the JCBA to allow it, and certainly flow-down rights in the event of a furlough.
4. It would require a revamping of the training program to operate both airlines under the same certificate. Their training shops are struggling with throughput right now. It would be the worst time in the world to add one or more small Jet types and try to get the FAA to certify the new type - not to mention then having to deal with their existing union on LCA/SLI issues for the new type(s).
5. Why on earth would they want to add another fleet type? They are struggling to deal with the type-swapping caused by early retirements during COVID already.
6. The majors do not - as of yet - actually have a shortage of applicants.

Among others…

Ok I see we are looking at the transaction completely differently, I’d say here would only be one company post transaction. A non-hub and spoke airline would not want a “regional” like you say.

One company after the transaction REQUIRES all of the above to be accomplished, plus DOJ approval and an agreed upon SLI. Given that the SLI might involve the transaction involving McCaskill-Bond to try to avoid a direct staple:

https://www.mondaq.com/unitedstates/...l-bond-statute

the major union is going to do everything they possibly can to stop it from happening. A guy flying 777s has zero interest in allowing himself to be displaced by someone who has been flying CRJ-200s for the last 20 years.

A major also would rather hire those guys on year one pay, rather than whatever longevity they have at Regional X.

Your list happens with any M&A if it was so prohibitive as you say then there would be no M&A which we know is far from the case with airlines. Your point about the SLI law is interesting because there is no precedent with it, we don’t know how it will look when used. So you jumped from no-staples to regional lifers displacing 777 captains, yet the law you posted doesn’t say no-staple and it doesn’t say 777 captains get replaced, it says “fair and equitable”. “Fair and equitable” is very wide, especially if both parties agree.
Again I wouldn’t bet on MESA, RP, OO being bought and integrated, but it could happen.

Why can’t you liquidate the regional in pieces and sell off the labor component in bankruptcy court using the judge to break all the contracts?

Anything COULD happen. But it won’t for the reasons given. And you need to better understand McCaskill Bond. It was expressly designed to prevent stapling, and no stapling has happened since it became law.