My only real concern would be missing your connection which would be extremely inconvenient and uncomfortable.

flightstats gives the inbound LH flight a good punctuality rating, which makes me happier. However, you have a one hour connection and SQ only flies 3 times a week from JED to SIN with no other obvious *A connections to BKK. Not good in the event of a major delay ex-FRA.

I think you need a 'Plan B'.