Doesn't seem like they are actually considering it and the circumstances are rather different.
Barca had to do something to generate funds and although you can argue it was the wrong something they did not have the option of simply ignoring their financial issues. United are not in anything like the sort of position Barca were in and will have far more sensible ways to raise capital if they need to. It is also worth bearing in mind that a big part of the justification for selling off a chunk of their La Liga tv money was due to two factors, firstly that the tv revenues have plateaued and don't look like increasing any time soon and secondly because the league as a whole was involved in similar scheme and Barca simply opted to negotiate on their own rather than collectively to get a bigger slice of the pie.
PL tv revenues are continuing to explode, already the PL generates far more revenue than any other European league and the most recent round of deals such as the renewal with NBC saw them almost doubling the money from the previous deal. It would take a monumentally stupid owner to choose to sell off a slice of those rights at this point and although the Glazer's are greedy leeches they are not stupid.
I agree with Everything you said except the bolded part, The Glazers are indeed a greedy leeches but they are also incompetent businessmen, and I'll explain why they are stupid.
United generated huge revenues in the post SAF era, yet, they (the Glazers) watched the club decline in football terms, just imagine if we were successful on the pitch between 2014-2022, or at least competing for the PL and regularly featuring in deep CL runs, United might've generated even more or even hit the 1B mark (in 2019 revenues were £627M, despite lack of success).
From the
Athletic
From 2012, United’s revenue grew year on year, other than a slight dip in 2015, until it hit a record £627.1 million for the year ending June 2019. It then dropped to £509 million in 2020 and again to £494.1 million in their latest set of annual accounts (2021).
Despite failing to achieve sustained success on the pitch in the past decade, United were still able to generate huge sums of money because of their illustrious history.
That, however, can only last so long.
So, it's not beyond the realms of possibility that the Glazers, who watched a cash cow like United decline, would consider selling TV rights,