Can H1B transfer petition filed after 60 days grace period be valid?

I'm on H1B and was laid of about 2 months ago and I am close to finishing my 60 day grace period. Fortunately, I was able to secure an employment in the mean time with an employer who is currently working on my transfer petition.

Unfortunately, due to the 2 new federal holidays before and after Christmas, my LCA certification is only going to be done on the 60th day of my grace period. My company's lawyers tell me that they can file my petition on the 61st day. They tell me that "USCIS shouldn't likely scrutinize the petition" even if they file on the 61st day.

The lawyers tell me that I should be ok even if filed a day later and they will do PP to expedite. They say they can argue with USCIS that it should be accepted as timely due to the unexpected last minute holidays declared by the whitehouse.

Has anyone filed the H1B transfer a few days after the grace period or have relatable near misses? Should I file a B1/B2 COS just for the few days? Can a transfer petition filed after 60 days grace period be valid?

I am hesitant to file the COS as my spouse is currently using H4 to study and the COS to B1/B2 would disrupt studies by a semester. Getting an F1 COS in the last 60 days seemed impossible and still is for the start of the academic year 2026. Are there any other visa options for my spouse to continue studies if I file H1B -> B1 COS?