If you read the article , you will see that mr Bjork examines also other possibilities

" In order to accomodate the criticism.."

Including faster probes

"All though I have used a relativly high probe velocity of 0.1c, it is a possibility that even faster probes could be invented and thus decreasing the exploration time significantly"

but it conludes

"Returning now to the result obtained in this paper, i see, to be able to conclude based on the results from my simulation that exploring the galaxi by sending out probes to visit the other stars is horribly slow.However unless travel methods are invented which give access to faster-than_light travel,there seem to be no alternative way to proceed than this proposed process.This could offer a possible explanation to the Fermi paradox."

You must not be a genius to argue :

" wow... if you increase the speed..."
" ohhh , why dont you use more probes.."
" Hey guy, if you ..."

Mr Bjork has taken into account even exotic possibilities such as the use of self replicating probes
Nevertheless the exploration time remains ...horribly slow