OK--per
this article here, the Rockets had 60.72 committed to 11 players going into the FA period (not including cap holds). Now, they've also agreed to new deals with Brewer (24/3) and Beverley (25/4)--combined salaries for those two for next year is 13.5M. Plus, the hold for Sam Dekker is 1.37M. So, their committed and agreed salaries for 2015 presently add to over 75M. Matching a non-tax MLE deal for McDaniels would put them over $80M.
Yes, they can use the non-tax MLE to match an offer for McDaniels, but it's important to note that would actually put them on a hard cap for the 2015-16 season; they would by rule not be permitted to exceed the luxury tax number. If they plan on keeping Terry and Smith, or signing (second-round pick) Montrezl Harrell, matching a McDaniels offer could make things very difficult.