It's not favoritism. It's JLP and the ship most closely associated with the character taking on TNG's most intractable foe in a climactic battle to end the story that's been told in dribs and drabs for decades across two series and a movie. If it were La Sirena it would have been bizarre and anti-climactic. Even if it IS favoritism it's still pretty immaterial. The USS Enterprise (any version, any bloody A,B,C,D,E,F,G) and the protagonists therein doing cool stuff is the ur-essence of Star Trek.
I mean, I think this speaks to a fundamental conflict between what different people wanted out of
Star Trek: Picard.
Simply put: The USS
Enterprise and Starfleet protagonists may be the ur-essence of
Star Trek, but it was not the ur-essence of
Picard as it was originally conceived. As originally conceived,
Star Trek: Picard was about a celebrated Starfleet officer long
after his career has ended, as he is approaching the end of his life, wrestling with his mortality, taking responsibility for his failures, finding meaning in spite of death and failure, and creating a new found family
outside of Starfleet.
Whereas PIC S3 was about... well, it was about Getting The Band Back Together. Which is fine.
But yeah, when the first half of the series builds up
La Sirena as the new hero ship outside of Starfleet and the it just gets ditched with no explanation halfway through S3, that's... well, it undermines the sense of dramatic unity
Picard originally sought to establish.
Using any ship other than the/an Enterprise in *this* episode, solving *this* problem, with *these* characters would be staggering creative malpractice. You may not be someone this applies to, but my feeling is that the fanbase in aggregate is at best indifferent to La Sirena.
I mean, even if that were true, that still doesn't mean it's good writing to just ignore it. It would have been better to have
La Sirena assisting the
Titan in Earth orbit while the
Enterprise dealt with the cube at Jupiter.
You can have action and thoughtful episodes.
I'll use VGR's "SCORPION" two-parter as an example.
Sure, but "Scorpion, Parts I & II" weren't all that thoughtful.