Well, Faerun is that kind of setting where Wizards and such are known to keep magical creatures as summons and familiars.
I know and i agree that Wizards would probably not mind ... but how about others? :P
And if you will answer keep in mind that we are not moving around metropolis where is wizard with some weird familiar on every step ... but in middle of nowhere, where druids are allready pretty sick of "those who dont belong to them".

And also keep in mind that events when demons draged to hell whole town can be still fresh is some memories.

like a temporary Approval drop or people being cautious
At least yes ...
I would certainly add for vendors one extra line telling people that they REFUSE to talking with them, as long as that *thing* is here.

Illithids are rare enough that people likely would not know how to react upon seeing one and if it doesn't outright attack them then it might be a bad idea to be outright hostile as it is something they do not understand.
On the contrary ...
People are more affraid of unknown, than known ... if you want proof, check the whole human history.

I dunno ... for myself its part of the fun that i cant drag my undead army to town with my Necromancer, that people are suspicious about me if my character belong to one of "unusual" races, or do some suspicious stuff like sneaking around.
