I wouldn't worry too much.

After what I've gathered, if he intended to leave Steemit permanently, the "sign" would be powering down ALL of his STEEM Power.
Seeing as that would practically reset his influence to 0, and make it very hard to build it up again.

the other currency tokens are more or less made to be cashed out or traded around anyway, so using them for that purpose is not alarming I'd think.

of course, if he's popular enough it would be a LOT easier to build up than for a new, unknown, user. But I think the point is still valid.