That is most likely right but the Tevinters could also see it as away to bolster their numbers to get back their empire. Tevinter do seem like opportunist.
If a particular mage is useful, they will be used as fodder against their enemies, If the mage is weak, they will be used as compost or research material, Foreigners are nothing to the Imperium.
Magic and Worth about the only two things that are respected there, Hawke maybe, just MAYBE could have gone there and been more or less accepted after defeating the Arishok.
But honestly, this is about, more or less, being a special exception to the rule rather then the norm.
I think that when, the consequences of staying are:
Certain death.
And the consequences of going are:
Slavery.
Cannon fodder.
Being invited in extremely low on the social ladder, (Tevinter does have quite a respect for magic even if they don't like the rest of Thedas - having magic is enough to move you out of being a slave, IIRC)
Being a blood-sacrifice.
That people will choose the option that's not 'certain death,' even if that option is 'maybe death'.
Tevinter doesn't even need to be honest about providing refuge. It just needs to be vaguely plausible that you'll live longer there than you will with the Templars.
And none of this covers the darkspawn, or the fact that the Qunari are unlikely to throw away their own mages, (and will also retain their cheap/superior explosive weaponry.)
Well this is true, i suppose but if it isn't obvious i am not of a mind of TKS.
I view Mages as a necessary evil in the world, one to be contained and then used when needed, not much else.
I don't believe in killing them pointlessly, Magic will just return again in, its rare but it continues to come, even from non mage blood lines.
It's far better to raise them, school them and then use them when it is needed and then return them to their cage.
You can't use a corpse to fight your enemies after all, Pragmatism will save Thedas, not some misguided notion of how magic must be destroyed and the Templar order transformed into a roaming army bent on the destruction of magic.
No, the Status quo is what will hold Thedas together and that is what must be restored.
It's quite simple.