^ No if it’s sent from Renako then maybe she’d have even less of a excuse to support the post because it means being loving with Ajisai is Renako’s desire and decision, even when Mai shown her love countless times.
So if she likes Ajisai’s post, it means she supports Ajisai’s pursuit of Renako, but it doesn’t necessarily mean Renako would accept. As is seen, she’s quite confident throughout the show that her feelings may be rewarded, even gave Ajisai reassurance about giving Renako more love.
But if she likes Renako’s post, then it can be directly seen as a green light for Renako to Pursue Ajisai, and is directly threatening her own status as the first pursuit girlfriend.
So yeah, she respects Renako’s choices and passions, even if it means taking in more humble pie than necessary.
And ultimately, they are all friends. Don’t want to make bad vibes in the groups of besties.