If I remember correctly (I might be wrong) you have to remove more than just the FD to change out that pinion seal - as it sits behind the ring/collar that holds everything in - to do that you need the BMW tool or make one on the mill and lather like I did and it took hours just to make the tool.
Good idea to remove the FD and take it in.
Note - there is no (preload) on this bearing - it is an angled roller bearing (set shoulder to shoulder) so it is shimmed in - pretty simple to change out once you get the thing apart.
As for the bottom FD bolt the OP asked about - it is a pain and I needed a big extension on my socket to do it with heat - terrible and I thought I would destroy either the wrench or the FD... but it eventually came out.
So lots of heat like others have said and it is fine - BUT the thread locker is on the inside part so best to heat the bolt side - when you do expect the fibre washer and or seals and bearing on that side to be toast so be ready to replace that - should anyways as it is cheap and easy for you to do it - I bought the bolt-pin-seals-gasket ring and bearings complete.