I mean if electability is your issue then this makes a darn good argument for Beto because if the Rs lose TX that is ballgame for the presidency.
At the very least this makes a darn good argument why Beto should be on the ticket should either Harris or Warren get the nomination (he won't be if Biden or Sanders is the nominee because we won't have an all white male ticket). Beto on the ticket makes Rs have to fight for TX.
Another takeaway - Castro is nowhere near the top despite declaring himself the Texan in the race right after the first debate. Why? Because, as I have been saying, many Texans soured on him when he didn't step up and run statewide in 2018
Poll link
Edited to add one caveat/call to action. This is registered voters versus likely voters. Among registered voters Ds have an advantage. Among likely voters Rs usually do. Given that disparity and these numbers this is a call to action for the D party to triple down on GOTV efforts in TX. as Beto has said constantly TX isn’t a R state. It is a non voting state.