I don't think that the bolded is quite right. I think it is closer to the following:
"When a player is placed on LTIR, their cap hit remains on the teams cap payroll and it continues to count as it always did. It also does not provide the club with additional cap-space savings that can be banked for future use while the team operates above the salary cap. Instead, LTIR provides relief if the club's averaged club salary, or payroll, begins to exceed the upper limit. "
LTIR FAQ - CapFriendly - NHL Salary Caps
I think this is the way it works, but am not 100% sure. Any capologists who know for sure? Thx ...
If MB is spending $8M under the cap as he is now, Weber's cap would still count and it would just close the gap to the cap maximum. That doesn't seem like something Molson would want if he is trying to save a few bucks during a rebuild. That is, assuming Molson really does want to commit to spend to the max cap limit to improve the team with active players. Interesting scenario in four years, paying $1M in salary to a Weber on LTIR while possibly acquiring $7.8M in cap relief that could exceed the upper limit.
If Weber is put on LTIR, and his salary being far less than his cap, he looks like he'd be useful trade for a team trying to save money while just spending to the cap floor, and not trying to improve during the outstanding length of his contract ... but how many teams like that are there? Few if any. The other trade option is if he is on LTIR and traded to a team that is already close to the cap maximum who are trying to dump a dud player, like as in the Horton case, but then the Habs get stuck with the dud player.
However, somebody is going to eat the cap amount for the length of the contract if Weber goes on LTIR.
PS: As an added note, the cap floor in 2017 was $55.4M ... while the lowest projected cap hit of all teams is Carolina and New Jersey at $61M. There are no other teams that would gain from acquiring a $7.8M contract to reach cap floor, they'd already be past any advantage point.