OP,
The above is wise.
Unfortunately some males have an inherent entitlement and think that their needs come ahead of everyone's, particularly their mothers.
Many is the son who think he has more entitlement to his mother's home than she has.
Very strong boundaries and NOT EVER giving him the impression this is an open ended arrangement is important.
Before he moves in make it VERY clear that you will review how things are working out.
Any efforts by your son to become territorial about YOUR home should be dealt with ruthlessly.
It often happens with returning sons that their mother having a relationship does not go down well.
A friend of mine had this during Covid when her son returned home.
She has a lovely home and her only son returned having lived away for 5 years.
She is now in a lovely relationship with a man she met through golf having been single for years.
Her son was off with him calling to the house from the minute he returned.
She asked her friends for advice and we were all united in telling her to nip it in the bud very firmly.
So she did.
She told him that she hadn't realised her doing him a big favour would result in him feeling entitled to be rude to her friend.
She told him that he would need to move out as she wasn't tolerating it.
She neither wanted nor needed his approval of her friendship with her boyfriend.
Her firmness resulted in him apologising and asking to stay.
He remained at home for a year and it was a very positive experience overall.
She cites her accepting no bullshit from him as key.
She still is with her lovely partner but has no wish to share her home.