One is yr mom's. If she feels sexy in 'em, then she's sexy in 'em. Period. End of. I mean, confidence is sexy in and of itself. But, honestly, if she's rocking that at 53, it probably DOES objectively look good on her. Very few women are still making objectively bad sartorial choices, at that age.
The only other opinion that counts -- if any -- is that of whoever is lucky enough to be in a relationship with someone who's awesome enough to rock leather pants at 53. Whoever that is. Yr dad, stepdad, etc.
The opinions of everyone else on planet earth are worth a sum total of zero.