While I don't really agree with the general assuption (70 years old in France in 2025 is quite a different thing from, say 70 years old in Russia in 2000 - people might even not be retired at that point and the variations in fitness are huge), I must say that it does feel like a crime committed by a younger male due to the method.I somehow cannot imagine a 70 year old female pensioner committing such a crime.
Then again, what other methods does any assilant really have, if they don't have a firearm? Strangling probably seems more risky and is even less likely to be used by a female. Poisoning? Might be a good choice for a local female, actually (especially if they hang out together). However, getting a good poison might be tricky and it would be easier to connect to someone, as it is clear that someone had to be close to her food. Unless you break in to poison the food at home, there will be other people in the public places she eats at.