Not true for all of us. Halicos likes to think of all nobles in Madinan colonies as Madinans, as long as they ask permission to leave first (yes, that's my get-out clause for Aurvandil and I'm sticking to it). He welcomed the Caerywnians back, and he'd welcome the Fissoans back. He wanted to help out, but... umm... my history is hazy on what happened :S
The "bond" is relatively recent. Caerwyn evolved during a long time without relations with Madina, I'd say it only really re-emerged and was forged right before the war against Astrum. Caerwyn had not asked permission to be formed, by the way.
True - and since Vallyn IS one of those Taselak nobles, one of the ones who stayed behind, he certainly holds strong ties to ensuring that Caerwynians are recognized as hailing from Madina, since Madina is the realm where all the Taselak nobles went to regroup after the SEI went under. He gladly welcomes back his old friends and brothers in arms - those ties go back well before Madina.
Not all Taselak nobles went to Madina, though indeed, most did. As I said, the few of us that went to Springdale instead ended up joining them in Golden Farrow anyways.
And obviously, that doesn't mean that ties between some nobles weren't maintained. Same happened with Caerwyn and D'Hara: I helped forge Caerwyn, so when I created a new character, I wanted to maintain a link, so I became an edler of VE and made it D'Hara's dominant religion. Madina/Caerwyn relations were similarly formed among other things thanks to Taselakians who had remained in Madina.
But at its origin, I don't think Madina was hostile, but it really was like "Eh, we didn't sanction this, we don't take any responsibility for what they do". I believe it's chronicled on the Dwilight Daily. Ties were forged later.