It isn't safe, the ladder should not be just propped against the guttering, health and safety no no...but then, we all did that didn't we?
I did for years on end, and far worse too, took all kinds of risks, more than you could shake a stick at in fact.
But the plain and simple fact is that what he is doing constitutes dangerous work practice.
There are a whole host of reasons why working that way is high risk.
Steep roof.
Sandy surface, possibly mossy too.
Ladder unsecured, risking ladder slipping away on guttering as weight is transfered form ladder to roof and afterwards from roof to ladder.
Risk of damage to guttering.
And obviously risk of damaging tiles.
These are not risks to poo-poo, just because many of us worked in this fashion before it doesn't make it right.
I think I've had more heart stopping moments on roofs than on ladders.
I've also walked around the corner of a house to find my employee groaning on the floor after he'd fell off the roof!
I've had broken tiles, cracked gutters, all manner of things...
Guidelines put in place to try and stop us working in this manner are not over the top, they make sense.
Ian