No, the poison is warfarin which is an anticoagulant that causes fatal internal bleeding in the rat. Do not worry about this at all, go ahead and munch a bunch!

Though I trust the poison isn't anywhere that birds and other small mammals could eat it...

Unfortunately Moon , when using poison baits, there will always be the potential for secondary poisoning no matter where it is placed.

You might want to establish precisely which bait they've used, there are several in common use as rodenticides (see link below). Its extremely unlikely that anything he's used will be taken up by the tree and its fruits. However, some baits are also classed as biocides and may have some impact on the tree's environment generally by affecting beneficial organisms which are present at the root. Knowing which one he's used and asking if there's any risk to your tree from it, or finding that out for yourself once you have the name, might be useful

http://www.pan-uk.org/pestnews/Issue/pn52/pn52p18.htm