The instruction "speed 250kts and descend FL070" you received doesn't stipulate that it applies at ARTIP therefore it is not a requirement to be at ARTIP at 250k and FL070. It's not an uncommon type of instruction and experience over many years has proven that for everyone who says "but the requirement is implied", there are an equal number who say not. If in doubt or you just want clarification then just ask, I do. Occasionally I get a comment from a checker when they are along for the ride and once again 50/50 chance the checker will go quiet when the reply I get from ATC is the opposite of what the checker was expecting so don't feel pressured to one way of thinking just because they are onboard.