Well, it sets a "precedent" of him staying there which may not be the most helpful for him realizing that he needs to get and keep it together himself.
Hitting bottom is different for everyone, but I truly think that addicts often
need to really get consequences for their addiction before they internally make a change.
One night in a truck won't be on the street and it will really motivate him
to get moving on the Sober House.
Staying with you makes it very tempting for him (and you) to extend the stay and he may find it so much nicer he may be demotivated to get out on his own.
With a check coming and a place to stay, I also think it may be tempting to spend the money on something other than housing.
Wishing both of you the best--of course--but I've read so many stories of relapse when the addict gets "rescued" right out of detox instead of figuring it out for themselves--