Does hiding previous experience of 3-6 months create any trouble in the new company?

One of my close friends is not liking the work in the current company due to the terrible WLB. He is planning to switch to a new company but doesn't want to show this current company experience of 3+ months. Have you ever come across such a situation? What's the best thing to do? If he reveals to the new employer then it won't be good on his resume because the company previous to the current one laid off 50% of employees and unfortunately he got affected too in that layoffs. So, due to tough market conditions he has joined a startup and realised that he can't sustain here for long.

Please guide if it's alright not to put the last 3 months experience in the resume and apply for new jobs.