It's been going on for a long time.
However, if a bus has been ordered to turn their radio off by Abbott, then it would be a transportation law violation
As to whether the bus thing is breaking immigration laws..it's complicated...
I know people who work with asylum seekers. They arrive in town via bus from the border. (I live in San Antonio) They stay at a shelter, then they get a bus ticket to join a host family. Usually the family is in another state. Then, they go.
The federal government also does mass transportation of migrants. (Usually unaccompanied minors)
However, there are some areas: Are the destination of the bus trips affecting the immigrations court dates? That is something that has not been answered.
There are plenty of ethical, good faith and abuse (use of power) questions.
Are individuals rights protected? It's complicated.
_______________________
Also the Garland has been sparring over Abbott with this to no avail...
https://www.houstonchronicle.com/politics/texas/article/Attorney-General-sues-as-Abbott-s-ban-on-16353403.php
Apparently, Abbott's bus scam prevents immigrants from their hearings. CBP got in Abbott, but did not charge him or anything. They just send him letters or something. Nothing gets done.
https://www.texastribune.org/2022/04/14/texas-migrants-buses-washington-dc/
https://www.politifact.com/article/2022/apr/08/gov-greg-abbott-says-he-will-transport-immigrants-/
I don't know the outcome of this case
https://int.nyt.com/data/documenttools/doj-lawsuit-challenging-tx-executive-order-no/46e51606e3b22e30/full.pdf
A year ago, Abbott was mad that he couldn't ship people out of the state.
Now he's shipping them out....
Abbott lost his case, but looks like he won on appeal
https://www.courtlistener.com/docket/60099074/united-states-v-state-of-texas/