Speaking on Friday, Sarwar said he felt “liberated” after calling for the prime minister to quit.
“Honesty is strength, not weakness,” he said when asked if he felt stronger in his position after Monday’s statement.
“We have seen dishonesty from this SNP government time and time again.
“I feel liberated and energised for the election campaign ahead, because, for me, my first loyalty and my first priority is to my country, Scotland.”
Earlier this week, the Scottish Labour leader also suspended MSP Pam Duncan-Glancy after “new information” emerged about her relationship with a convicted sex offender, former Moray councillor Sean Morton.
Duncan-Glancy said she was “deeply disappointed” by the decision, which she said had not been fully explained to her.
Lord Doyle, Starmer’s former director of communications, was also suspended from Labour’s Westminster party over his links to Morton.
The prime minister has been heavily criticised by opposition MPs for his handling of the controversy.