Kean had to hire a round-the-clock bodyguard last month after fearing for his safety following protests by fans calling for him to be sacked.
Blackburn, owned by Indian poultry giant Venky's, are battling against relegation and lie three points above the drop zone in 16th place after being bottom of the table in January.
"It just shows you how things can change when you dig in and don't let things get to you. Now, no-one talks about their fans and any protests," Ferguson told a news conference at Old Trafford on Thursday.
"He [Kean] has held his dignity very well and he deserves praise from everyone including his own supporters," said Ferguson of his fellow Scot.
"I'm sure a lot of them will be wishing they hadn't done that because he's certainly shown his mettle during those times when things were difficult for him."
Ferguson, who arrived at Old Trafford in 1986 and has become the longest serving and most successful manager in English football, also faced calls for his dismissal in 1989 after a dismal start to that season.
He jumped to Kean's defence in December as well, urging Blackburn fans to give the manager a break and saying he had "never seen anything as bad" as their barracking.
Leaders United are three points clear but closest rivals Manchester City could reclaim top spot on Saturday when they host Sunderland.
Ferguson said centre-back Rio Ferdinand would be fit for Monday's match after being substituted during United's 1-0 win over Fulham on Monday but Nani remained unavailable.
"It'll be the same squad as Monday night with no changes," said the manager.
"We expect Nani to train tomorrow but the game will come too soon for him. Rio is OK, he just felt a bit stiff. We know the situation with that. We addressed it right away and put Chris Smalling on. He's fine."
