As far as Ican see you don‘t take any weld out at all as the whole bolt-construction is only welded on from the outside. Weld (seam) itself is structural imo :-)
You basically take out the remaining pipe which was put throught the seattube horizontaly while manufacturing.
can you give us some info on the tools used to make the hole? 34.9 hole saw or smaller like 34mm? Any photos?
As far I can see, the pivot mount is welded on outside so sawing the insode out should be ok. Do you have any longterm experiences?
Thanks in advance