The SNP (like the English Govt to be fair) have form for slipping stuff like this out into the press to distract from the real issues:
Scottish NHS on it's knees. Childrens wards being closed. Waiting lists horrendous (patients being sent to England for treatment too)
Attainment gap in education the widest its ever been. Slashing of funding for FE colleges. Scottish Curriculum for 'excellence' widely derided by educational experts and providers.
Economy tanking even faster than UK economy in general.
Oil in particular (which was supposed to be the pot of gold which would make Scotland impervious to all woes)
Failure to be taken seriously in Europe re staying in EU after Brexit.
Oh, yes, and there was that failed Independence Referendum (which they will rerun as soon as she feels there is a snowflakes chance it will go Yes this time). That is the real bugbear and the reason the SNP have not concentrated properly on anything else for the last decade.
So yes, whinging on about flags is something the SNP do and will continue to do both because they really ARE that petty and because it is a handy smoke screen