Hey there,
The reason Guest can't switch profile is because that switch profile link points to your "Home" Easysocial (User) dashboard menu which you set that access only registered user can able to access.
This is why it doesn't redirect to the correct page after you click on that switch profile link.
I've help you removed that profile type you selected from this menu 'Inscription' (Easysocial Registration layout menu), so that switch profile link no longer point to this "Home" Easysocial (User) dashboard menu, so guest user can able to access this link now.
May i know you would like redirect guest user to the registration form page by clicking on this menu link 'Inscription' on the page?
If that is the case, you have to set back that profile type from this menu 'Inscription' (Easysocial Registration layout menu) then create a hidden menu for this menu type (Easysocial Registration layout menu) on your site.
Do take note, do not select any profile type for this menu, so that switch profile link can able to point to this menu.
Do keep us update if the issue still persists.