No he's not. Where do you come up with this nonsense? Give some examples where GM's rebuilt a team in three or four years if you think five years is more than a traditional timeline. I'll wait. Because there isn't one. He needs to start having some progress, which is already happening, next season. This is a big off-season for the UHC.
Rebuilds aren't a linear timeline, there's so much involved, strength of draft and luck being the obvious two. Armstrong was hired in September of 2020, that winter they decided to tear it down and rebuild starting from the 2021 draft, so he's only three and a half years into a rebuild. The 2025 draft will be his fourth.
Look at the Chicago Blackhawks, it took them six drafts to assemble what is considered a modern day dynasty before they had the right players to win a Cup. Starting with Duncan Keith in 2002 and finishing with Patrick Kane in 2007.