Hope this will enlighten u in some way.As i have experienced there r some AIKIDO styles that r very particular when it comes to the ranks.Example:
1.Some styles do not allow students from other affiliations to train in their Dojo.
2.Some allow u to train but u have to go back to white belt.
3.There r also others who let u train regardless of sytles and ranks.
4.There was also this Dojo where in they allow u to train but u have to go down one kyu from ur current rank.
I'm from a KI AIKIDO Style in our Dojo we welcome every AIKIDOKA regardless of AFFILIATION , STYLE and RANK.But there r also some KI AIKIDO Dojo's that don't.
So, i think it's also the Sensei's decission whether to welcome them or not. But for me to PROMOTE,and the ADVENCEMENT or PROPAGATION of AIKIDO why not WELCOME ALL.
SCOUT "TUOCS" TUMULAK
Head Instructor-TIMEX DOJO, PHILIPPINES