Digress all you want, the term ‘some sympathy’ is fairly transparent.
Anyone who was aware of the history or who was genuinely sympathetic would not prefix it with ‘some’.
Similar to -
“She has some knowledge” = vaguely aware but knows nothing.
”I have some understanding” = I have no knowledge but don’t want to admit this.
However I will ‘digress’ and go through your points.
I have not shown any ‘anger’ but the fact you have questioned my religious beliefs (or lack of) is interesting, I fail to understand why this is relevant which is why I won’t be labouring the point.
Your points about a changing society and secular schools reflecting this again on the face of it make sense, what you seem to be failing to grasp however is the reality of the situation is very different.
So I will try again.
There was a well-accepted and valid reason for catholic schools in Scotland.
These have been built up over a long time.
They have complex ownership structures with legally binding agreements, the state cannot just simply dictate what happens in them or assume ownership of many of them.
Although religious attendance is declining the schools rolls are not, although the church may have less of a role on a day to day basis, families still decide they want a catholic education for their children.
Now, and here is the part you seem to be having trouble with.
If the government announced the end of catholic education, a thing that is extremely valued by a large part of the population then do you really believe it could be implemented with no resistance?
There would be parent protests, trade union involvement, legal challenges (which would very likely succeed due to previous legislation), political pressure and also an absolutely astronomical financial bill.
The social factors would, unlike the educate everyone together fairytale and unicorn world you described, cause a massive spike in sectarian tension, allowing a picture to be painted that the state could just destroy a key tenant of catholic culture without any recourse.
The triumphant behaviour of the more bigoted parts of the Scottish population would be a sickening sight in itself.
As for the ‘hysterical’ thought of police having to drag people out of schools, that is very possible.
All it takes is sit-down protests, a tactic that would likely be deployed if the state were forcing this, how else would they be cleared?
Another question to ask yourself is if this is such a good popular idea then why do no politicians of any note make any effort ti make it happen?
The answer is quite simple, they are well aware of the minefield it would cause and the damage to society as a result. It would likely end their careers.
It will never happen.