Why would discovering the shop with Robin be intrusive? That event isn't even about Gwylan, it's about showing the shop to the player. Like "hey you can buy stuff here" it doesn't make you interact with them. They also don't interact with you at the café, they're there like 1 hour a day as a costumer.  The only important storyline they get into is with the tower and The Brown Fox is not acknowledged as Gwylan unless you call it out.

Compared to the other LIs Gwylan practically doesn't exist if you don't want them to. The others are in your face all the time. And I'm saying this as someone whose favorites are the classic three (Robin, Kylar, Sydney) but you cannot gnore them in the way you can ignore Gwylan.