Oh i think i understand well - and yes your arguments are good
Then next version - Rogue knows Priest will come after 15s - so what he just hides for the first seconds and uses invis pot just for the last 15s.
And if the priest comes earlier - just take invis until priest immune is over - oneshot him (it´s still an alt)... hide again with escape or whatever,...
I know it´s a thing barely to do - but as long as it is possbile to cap without being able to be interupted (with all immunes, potions, skills whatever) people will try and also succeed.
Thats why I like the idea of doubling the cap-time more than just 5s - maybe 25 is also enough.
But I prefer even more the idea of guards attacking the occupier even in invis or the cap only when all guards are down - maybe even combinations of all 3 ideas.